A Brief Overview of the Arthropods (Phylum Arthropoda)
All arthropods are believed to have descended from a common ancestor, the annelids, more commonly called segmented worms. They are grouped into three main subphyla: Uniramia, Chelicerata and Crustacea.
The subphylum Uniramia contains the classes Diplopoda, Chilopoda and Insecta. Diplopoda are millipedes and Chilopoda are centipedes. Insects include beetles, flies, butterflies, and many other six legged creatures. Most Uniramians live on land and can fly. They have unbranched legs, unlike crustaceans. Most uniramians breathe using a tracheal system, comprised of spiracles, tracheae and tracheoles. All possess one pair of antennae.
The subphylum Chelicerata contains the classes Arachnida, Pycnogonida and Merostomata. The Arachnids include spiders, mites and scorpions. Class Merostomata are horseshoe crabs and class Pycnogonida are sea spiders. The most obvious defining characteristic of the entire subphylum is their fangs and/or pinchers. All Chelicerates have eight legs and lack antennae.
The subphylum Crustacea contains the class Malacostraca. This class is where marine animals such as shrimp and crabs are found. There are a few terrestrial representatives, such as pill bugs. Crustaceans have branched appendages and their exoskeletons are hardened with calcium carbonate. A very unique characteristic of crustaceans is that they have two pairs of antennae, where insects only have one. They have legs attached to their abdomens in addition to the ones on their thorax and have three pairs of chewing appendages. A final characteristic of Crustaceans is that they breathe with gills. This limits terrestrial Crustaceans such as pill bugs to very damp environments.
This table outlines the differences found in the phylum Arthropoda:
| Characteristics of each Arthropod Subphylum | ||
|---|---|---|
| Subphylum | Distinguishing Characteristics | Examples |
| Uniramia |
|
|
| Chelicerata |
|
|
| Crustacea |
|
|
Arthropod Resources for Different Grade Levels
Grade School
Exploring Urban Biodiversity - City Bugs
Includes much information and many activities pertinent to younger students. A good starting point
for teachers who feel a need to update their own background prior to engaging in different activities.
Largely taxonomy-based.
Using Live Insects in Elementary Classrooms for Early Lessons in Life
Program dedicated to introducing health topics to children in kindergarten through third grade. Printable
collection of twenty integrated lessons with science and math activities that use live insects. These lessons
are aligned with National Science Education Standards (NSES).
Middle School
Butterfly Flower Gardens
General butterfly information and guide to building butterfly-attracting gardens. (Recommended by the students at After-school Care Programs.)
High School
Advanced Arthropod Studies Curriculum
Supplement to arthropod study and activities students typically encounter in high school level biology, ecology
and environmental sciences classes. Each component may be used individually or may be integrated with others in
whatever way is most meaningful to individual teaching situations. These activities lend equally well to cooperative
or independent learning situations. All of these projects require use of the Internet-based resources as a the major
resources in gaining further knowledge. Each project is tied to real-world knowledge, not memorization and abstractions.
Many of the projects have a myriad of project extensions. Curricular activities are:
- Microarthropod Collection and Examination (PDF)
- Microarthropod Variation and Taxonomy (PDF)
- Quantitative Study of Arthropod Ecology (PDF)
- Scientific Proposal Writing Using the Bugscope Model (PDF)
- Introduction to Online Scientific Journals (PDF)
Insect Order Information
(Including links to "Best of the Web" for each insect order)
Try our quick jump list to find what you are looking for faster:
Anoplura
Coleoptera
Collembola
Dermaptera
Dictyoptera
Diplura
Diptera
Embioptera
Ephemeroptera
Grylloblattodea
Hempitera
Hymenoptera
Isoptera
Lepidoptera
Mallophaga
Mecoptera
Neuroptera
Odonata
Orthoptera
Phasmida
Plecoptera
Protura
Psocoptera
Siphonaptera
Strepsiptera
Thysanoptera
Thysanura
Trichoptera
Zoraptera
Proturans are minute whitish creatures that range from half a millimeter to one and a half millimeters in length. Their head is conical and lacks antennae and eyes. Their mouthparts, which do not bite, are used to scrape off food particles which are digested when mixed with saliva. The larvae begin with 9 segments and acquire one after each molt until they are an adult with 12 segments. The first three segments have styli which are bristlelike, and the first segment has legs which are held up like antennae and act as sensors.
These creatures are also called hexapods and reside in moist environments such as soil, humus, and bark. Their diet consists of decomposing organic matter and fungal spores.
Links:
Protura (PDF)
Order Diplura (Dipl=two, ura=tail) - Diplurans
Diplurans are hexapods that are mostly similar to silverfish and bristletails. However, they possess only two caudal filaments and are not covered with scales. They also lack compound eyes, have 1 segmented tarsus, and possess mandibles which are withdrawn into the head. Diplurans have styli on 6 or seven of their segments.
These pale creatures are found in damp places such as in soil, caves, and rotting wood.
Links:Diplura (PDF)
Order Collembola (Coll=glue, embola=wedge) - Springtails
This creature's common name, springtail, comes from the forked structure (furcula) that allows them to fly through the air. These whitish hexapods make use of this ability when they are disturbed or when mating. Springtails 3 to 6 mm in length can jump 75 to 100 mm.
Springtails can have as many as eight ommatidia (units of a compound eye) while others are nearly or completely blind. Species of Collembola which are herbivores or carnivores possess mandibles which are concealed within the head. In contrast, some species are fluid feeders and possess styletlike mouthparts. A collophore (tubelike appendage) is found on the first abdominal segment. Its tip holds an eversible sac which is known to play a role in the intake of water.
Most species live in concealed areas such as in leaf litter, decaying logs, and fungi. Other species can be found on the surface of freshwater pools and along the coasts. Most feed on decaying plant material, fungi, and bacteria. However, arthropod feces, pollen, and algae have also been found to serve as food for Collembola.
Links:
Collembola (PDF)
Order Thysanura (Thysan=bristle, ura=tail) - Bristletails, Silverfish
Silverfish are characteristically identified by their three taillike appendages at the end of their abdomen. They are moderately sized, elongate, flattened, and are covered with scales. They also possess mandibles, compound eyes (absent in some), and ocelli (simple eyes) in some. The tarsi have three to five segments with the taillike appendages located on the last segment. These appendages consist of the cerci and median caudal filament. the abdomen has 11 segments which bear styli.
Most silverfish occur outside and feed on plant materials. They can often be found under rotten logs, leaf debris, and stones. Species that are found indoors usually reside in areas that are damp and dry such as bathrooms and basements.
Links:
Archaeognatha (PDF)
Silverfish
(PDF)
Order Ephemeroptera (Ephemero=short-lived, ptera=wings) - Mayflies
Mayflies are soft-bodied insects which are often identified by their characteristic two or three long threadlike tails. The adults have membranous wings with many veins. These wings are held above the body when the creature is at rest. Most mayflies have large triangular front wings and small rounded hind wings. However, in some, the front wings are elongate and the hind wings are virtually nonexistent.
Mayfly nymphs reside in aquatic areas and differ in their daily behavior. Some our active while others burrow y habit. Their other identifying characteristics (besides the threadlike tails) are the gills that can be found along the abdomen. Subimago stage (occurs between nymph and adult) occurs when a mayfly rises to the waters surface, molts, and flies the short distance to shore landing on vegetation. The next day it molts again to become an adult.
Mating, among adults, occurs during swarming flights. These swarms can range in size from small groups to swarms resembling clouds. The swarms begin as all male until finally females join and are seized by the male. Mating takes place in flight and the eggs are laid on the surface of the water. Often mayflies emerge from the water simultaneously which often causes problems for trains and traffic.
Mayflies are important to the diets of many animals, especially fish. Therefore the number of mayflies can serve as a biological indicator for their surroundings.
Links:
Ephemeroptera (PDF)
Order Odonata (Odon=tooth) - Dragonflies and Damselflies
Odonata are well known as beautiful colorful insects that fly. Damselflies tend to be more delicate and slender. The nymphs are aquatic and the adults generally reside close to the water. At both stages, Odonata are predacious and beneficial to humans. The adults have four wings which are elongate, membranous, and have many veins. They also have large compound eyes which tend to make up most of the head. The antennae are small and bristle like, and the abdomen is elongate. The males have cerci (appendages at the end of the abdomen) which are used for clasping during mating. Odonata possess chewing mouthparts. They range from 20 to over 135 mm in length.
The nymphs are aquatic and use gills to breath. Damselfly nymphs are characterized by their gills which come in the form of three leaflike structures at the end of the abdomen. these nymphs move by undulating through the water. Dragonfly nymph have ridges in the rectum that work as gills. By taking in water via the rectum and expelling it, these nymphs are propelled through their water which is their chief means of locomotion. Both types of nymphs feed on small aquatic organisms and use there segmented labium to catch their prey. When fully grown, the nymph emerges from the water to undergo its final molt. After the final molt it takes about half an hour for the adult to fully expand itself. It then takes two to three days to gain full wing strength and another week until its coloration is fully established. In most cases the males are more brightly colored.
Damselflies have a life span of 3-4 weeks while dragonflies may live as long as 6-8 weeks. Mating occurs in tandem (joined) and this usually occurs during flight. Males are territorial and will often chase off other males from the desired female. Odonata arrange their legs in a basketlike fashion to catch their prey which usually consists of small flying insects.
Links:
California Dragonflies and Damsel Flies
(PDF)
Odonata Photo Archive
(PDF)
Items of Interest to Odonata (Dragonfly) Enthusiasts
(PDF)
Odonata
(PDF)
Order Plecoptera (Pleco=twisted, ptera=winged) - Stoneflies
Found near streams or lake shores, stoneflies, are small insects that are usually flattened and drab in color. They have four membranous wings which are occasionally reduced or absent in males. Cerci are present on the three-segmented tarsi and the mouthparts are chewing.
Development in stoneflies is a simple metamorphosis. The nymphs are aquatic, have long antennae and cerci, and have branched gills. Unlike mayfly nymphs, stoneflies lack the middle caudal filament leaving them with only two. Mating occurs in response to acoustic sounds made by drumming the abdomen upon a substrate. The drumming pattern is different for each species.
Links:
American Stonefly Web Page
(PDF)
Plecoptera (PDF)
Order Orthoptera (Ortho=straight, ptera=wings) - Grasshoppers, Crickets, and Katydids
Most in this order are plant feeders and are well known to be troublesome to farmers and their crops. They may be both winged or wingless. If winged, they will have four wings consisting of a leathery front pair and a heavily veined back pair. The body, cerci, and antennae are elongate and some species have a long ovipositor. They have chewing mouthparts and simple metamorphosis.
The Orthoptera are best known for their ability to sing. This is done by stridulation which is rubbing one body part against another. The tympana (oval eardrums) are located either on the sides of the first abdominal segment (short-horned grasshoppers) or at the base of the front tibiae (long-horned grasshoppers and crickets). Each species has a different song which is characterized by its rhythm. Most of the singing is done by the males in order to attract the females. The female recognizes the species specific song and approaches the male. In some cases, the male sings an aggressive song if his territory is being invaded by another male.
Links:Cricket Science (PDF)
Grasshoppers and Crickets (PDF)
Orthoptera (PDF)
Orthoptera (PDF)
Orthoptera Species File (PDF)
Order Phasmida (Phasma=phantom) - Walkingsticks and Leaf Insects
In the midwest, species of phasmida are elongate and sticklike with wings either reduced or absent. They are slow-moving herbivorous insects which use mimicry (their twiglike appearance ) to protect themselves. They can emit a foul smelling order which is also used as a means of defense. Walkingsticks can regenerate lost legs and when they are numerous can cause great damage to trees.
The egg stage is overwinter and often hatch two years after they are laid in the spring. The generation lasts one year. Walkingsticks begin greenish in color but turn brownish as they mature.
Links:
Phasmatodea (PDF)
Order Dictyoptera (Dicty=net, ptera=wings) - Cockroaches and Mantids
Cockroaches are known to be fast runners and poor flyers. They are flattened and their head is concealed by the pronotum. Cerci can vary in length while the antennae are generally long. The eggs are held in capsules known as oothecae which are either deposited right after formation, carried around on the abdomen, or enclosed internally in a uterus. They are considered general eaters and household pests.
Mantids are large creatures with an elongate prothorax and abdomen. Unlike cockroaches, mantids are slow moving and have legs modified with spines to catch prey. Mantids are also considered to be the only insects which can turn their head fully. Their eggs are enclosed in a case known as an ootheca and are deposited onto twigs or grass stems. If no other food is readily available, the nymphs eat each other until one remains. The males are eaten after or during mating and in some species no males have been fond. These creatures are often used for pest control but can become pests themselves when they cannot differentiate between damaging and useful insects.
Links:
Cockroach Facts
The Cockroach Homepage
(PDF)
Praying Mantids
(PDF)
Blattodea (PDF)
Mantodea (PDF)
Order Grylloblattodea (Gryll=cricket, blatta=cockroach) - Rock Crawlers or Icebugs
Commonly called rock crawlers or icebugs, Grylloblattids are slim, long, and yellowish brown or grayish. They have no wings and have long antennae.
Females possess a sword shaped ovipositor. They have chewing mouthparts and undergo hemimetabolous development. Rock Crawlers live in mountains and high altitudes, under rocks, logs and debris. They also live in snow fields, ice caves and other low temperature habitats. They are omnivorous and usually nocturnal.
Links:
Grylloblattodea (PDF)
Grylloblattodea
(PDF)
Order Dermaptera (Derma=skin, ptera=wings) - Earwigs
Commonly called earwigs, these insects' most prominent feature is the forcepslike cerci. They may or may not have wings. If they do, the front wings are short, leathery and veinless while the hind wings are membranous and rounded. Earwigs have chewing mouthparts and undergo simple metamorphosis. Earwigs eat dead and decaying vegetation, living plants, and occasionally other animals. They are mostly nocturnal. Of the winged variety, some are good fliers while others only fly when forced. Eggs are laid in burrows or under debris and guarded by the mother. A few species have glands on the dorsal side that emit a foul -smelling fluid as a defense mechanism.
Links:
Dermaptera
(PDF)
Dermaptera (PDF)
Order Embioptera (Embio=lively, ptera = wings) - Webspinners
Their common name is webspinners and unlike most silk-producing insects, the silk glands and spinnerets are located in the front two feet, not in the mouth. They have somewhat flattened bodies and are between 4 and 7 mm long. Webspinners have chewing mouthparts and undergo simple metamorphosis. The legs are short and stout. Most males are winged but some have vestigial wings or no wings at all. The front pair of wings is quite similar to the hind pair. Females are always wingless. Strangely enough, within one species there may be winged as well as wingless males. Webspinners have 10 segmented abdomens with two-segmented cerci on them. Some males have only one segment on the left cercus. One species is known to be parthenogenetic (able to reproduce asexually).
Webspinners live in self-spun silk homes in debris, cracks in the soil, under rocks, or under bark and among plants. Most species are social and live in colonies. All young are able to spin silk as they grow up.. Large and cylindrical and laid in the silken homes where they are watched by females. As a defense mechanism, webspinners may feign death or run backward rapidly. They feed on various plant materials.
Links:
Embioptera (PDF)
Embiidina
(PDF)
Order Isoptera (Iso=equal ptera=wing) - Termites
Termites, as Isopterans are commonly called, live in social groups and have a highly advanced caste system. In one colony there may be winged or wingless individuals, depending on caste. Winged individuals have two pairs of membranous wings that are almost identical in size and venation, hence the name Isoptera. They have chewing mouthparts and undergo simple metamorphosis. Termites are similar to ants in superficial appearance and social structure but there are some important differences. Termites are lighter colored and have softer bodies than ants. Ant's hind wings are smaller than their front; termite's wings are the same size. The termite cast system has moth sexes as workers and soldiers, with all nymphs as workers and ants these positions are fulfilled by adult females only. Termites appear similar to cockroaches and are sometimes placed in the same as them. One species carries its eggs in a structure that closely resembles a cockroach's ootheca. Termites often groom each other, probably because of pheromones. Besides their well known diet of wood, they eat the cast skins and feces of other termites, and dead termites.
These insects live in moist underground colonies or dry aboveground habitats. Some African species make nests up to 9 meters (30 ft) high. Dry wood termites, who live without contact to moist soil, obtain all their water from the oxidation of food, the waste water from respiration. Termites digest the cellulose in wood with the help of flagellated protozoa or bacteria which live in their digestive tracts. If these helper organisms are removed, the termite will eventually starve to death. In order to transport these micro-organisms to their young, termites undergo a unique process called trophallaxis. Trophallaxis involves the transfer of liquids from the anus of one termite to the mouth of the other.
Links:
Dr Don's Bizarre Termite Page
(PDF)
Termites
(PDF)
Isoptera (PDF)
Order Zoraptera (Zor=pure aptera=wingless) - Zorapterans
These tiny insects (3 mm) are similar to termites in appearance. Both sexes may be winged or wingless. The hind wings are smaller than the front. Adults eventually shed their wings, as in termites and ants. Wingless forms also lack any eye structures while winged forms have compound eyes and three ocelli. Zorapterans have 10-segmented abdomen. They have chewing mouthparts and undergo simple metamorphosis. This order contains only one family, Zorotypidae, and one genus, Zorotypus. There are 22 known species in this genus. Colonies may be found under bark and in rotting logs. Zorapterans eat fungus spores and small dead arthropods.
Links:
Zoraptera (PDF)
Order Psocoptera (Psoco=rub small, ptera=wings) - Psocids
These small (6 mm) soft-bodied insects may be winged or wingless. They have four wings with the hind pair smaller (and rarely vestigial). The antennae are fairly long and there are no cerci. Psocids, often called book lice, have mandibular mouth parts and simple metamorphosis.
Psocids feed on molds, fungi, cereals, pollen, fragments of dead insects, and similar materials. They lay eggs singly or in clusters and sometimes cover them with silk or debris. Some species are gregarious and construct webs.
Links:
BOOKLICE
(PDF)
Booklice
(PDF)
Order Mallophaga (Mallo=wool, phaga=eat) - Chewing Lice
These wingless parasites are often called chewing lice. Because they prey on birds and mammals, they are often also called bird lice. They have small compound eyes and no ocelli. Chewing lice have chewing mouthparts and undergo hemimetabolous development. They are major pests of many domestic animals, especially poultry. They cause skin irritation, emaciation and exhaustion of the host. The host may then be killed by the lice or by a secondary infection.
Mallophaga species are very particular in their host selection. A few may have no more than six hosts, however. They feed on bits of hair, feathers or skin of the host. They do not appear to use humans as a host. Females secure up to 100 eggs on the hair or feathers of the host. Chewing lice get to one host to another by contact between hosts, as in a nest. They will soon die without a host.
Links:
Mallophaga
(PDF)
Order Anoplura (Anopl=unarmed, ura=tail) - Sucking Lice
These parasites are called sucking lice. Unlike mallophaga, they have sucking mouthparts and are parasites of only mammals and not birds. They are wingless and may be eyeless. The mouthparts consist of three piercing stylets that are retracted into a cavity in the head when not in use. The tarsi (feet) of anoplurans consist of a large claw and a process that acts like a thumb. This setup allows the sucking lice to cling to its host's hairs. Anoplurans undergo hemitabolous development.
Sucking lice are extremely specific in their hosts. They infect many mammals including humans. "Cooties" are a representative species of this order, as are head lice. Females lay eggs similarly to Mallphaga, by attatching them to hairs or clothing fibers. Sucking lice may cause skin irritation and they spread certain diseases.
Links:
A different Tempo of Evolution in Birds and their Parasitic Lice
(PDF)
Lice
(PDF)
Introduction to the Phthiraptera
(PDF)
Anoplura
(PDF)
Order Thysanoptera (Tysano=fringe, ptera=wing) - Thrips
Thrips, as thysanopterans are commonly called, are lender and may be winged or wingless. When they have wings, they have four and the wings have a fringe of hairs on them. Thrips have sucking mouthparts. Some thrips have ovipositors. Thrips can undergo parthenogenesis and some species are not known to have male members. Thrips undergo a kind of intermediate form of development: there are two larval stages followed by two to three inactive pupal stages. This resembles hemimetabolous development in that preadults have external wings but resembles holometabolous development in that there is a pupal stage and some wing development is internal.
Thrips use their sucking mouthparts to feed on plant juices and those with ovipositors use them to lay eggs in plant tissue. Those that do not lay eggs on or under bark or flower parts. Because of these habits, many thrips are considered pests. They destroy plant cells and may spread disease. A few thrips eat fungus spores, some eat small arthropods and a very few may bite humans.
Links:
Introduction to the Thysanoptera
(PDF)
Thysanoptera
(PDF)
Order Hempitera (Hemi=half, ptera=wings) - Bugs
Hemiptera gets its name from the structure at the base of the front wing. It is called hemelytron and is characterized by its thickened and leathery appearance. These creatures have piercing-sucking mouthparts which are in the form of a beaklike structure. They are most commonly identified by the presence of a scutellum (triangular part of the thorax). The head has large compound eyes and antennae that can be either short or long. The adults have scent glands which emit and unpleasant odor if the bug is disturbed. Most Hemipterans have well developed wings, however, some species have short wings or no wings.
Eggs are laid on plants, in crevices, and in some cases are just dropped. Development consists of a simple metamorphosis most of which have five nymphal instars. Many Hemipterans feed on plant juices and threaten crops while others are predacious and considered very beneficial.
Links:
Hemiptera and Homoptera
(PDF)
Hemiptera
(PDF)
Hemiptera - Suborder Heteroptera (PDF)
Hemiptera - Suborder Homoptera (PDF)
Order Coleoptera (Coleo=sheath, ptera=wing) - Beetles
The well known beetle, the common name of Coleopterans, is the largest order of insects. They account for 40 % of all the known species in the class Insecta. Though this order contains much variety, most beetles are easily identified as such by their similar wings. They tend to have four wings with the front pair thickened, leathery, or hard, and meeting in a straight line down the middle of the dorsal side. These outer wings serve to protect the inner pair and the insects. The hind wings are the only pair used for flight usually. The front protective wings are called elytra and may be rough or shiny and may be brightly colored or dull.
All beetles have chewing mouthparts that can be quite strong. Beetles undergo holometabolous development. Some are predacious and a very few are parasitic but most are scavengers and plant eaters. Due to their diversity, they live in practically all climates inhabited by living things.
Links:
Coleoptera
(PDF)
Beetles
(PDF)
Order Strepsiptera (Strepsi=twisted, ptera=wing) - Twistedwinged Parasites
Commonly called twistedwing parasistes, these insects are mostly internal parasites of other insects. Males differ greatly from females in structure. Males have wide heads with compound eyes on the sides. Males also have fan shaped antennae. Their forewings have evolved into clublike structures and the hind wings are membranous and with out venation. Females are without legs, wings, antennae and often eye and remain in the host their entire lives.
The females remain in the host with only their heads protruding. Males leave the host and find females to mate with. The newly hatched, well-developed larvae leave the female and fall from the host to the ground or to plants.
Twistedwing parasites enter their insect hosts as larva through joints or sutures when the host itself is still in its larval stage. From there they undergo what is called "hypermetamorphosis": They molt into another, less mobile, larval form and feed in the host's body cavity. From there they undergo holometabolous metamorphosis. Hosts are not usually killed by infection but may be injured. The shape and color of the abdomen may be changed and the sex organs of the host may be damaged. The male usually causes more damage to the host than the female. Common hosts are various species from the orders Orthoptera, Hemiptera, Hymenoptera and Thysanura.
Links:
Strepsiptera
(PDF)
These creatures are soft-bodied and have four membranous wings with multiple veins. The mouthparts are mandibles, the antennae are long, and the cerci are absent. These creatures experience a complete metamorphosis. The larvae are predacious with the exception of a few species which are parasitic. Some species spin silk cocoons which are produced by the Malpighian tubules and are spun from the anus. Adults whose larvae are aquatic are generally found by water throughout their life. The adults are poor flyers and are predacious.
Links:
Neuroptera
(PDF)
Aquatic Neuroptera
(PDF)
Neuroptera (PDF)
Order Mecoptera (Meco=long, ptera=wings) - Scorpionflies
Mecopterans are aptly nicknamed scorpionflies because they look like scorpions with wings. The males have bulblike genital segment that resemble the stinger of a scorpion. A second main distinguishing feature is the elongated face most species have. Most have four long wings. They have chewing mouthparts and undergo holometabolous development. Adults are either predators or scavengers of other insects. Few are plant eaters. Scorpionflies inhabit damp, shady wooded and wetland areas.
Links:
Mecoptera (PDF)
Order Trichoptera (Tricho=hair, ptera=wings) - Caddisflies
Caddisflies resemble moths in that they have four membranous wings that are often hairy or scaled. They have long slender antennae, are dull in coloration, and have chewing mouthparts. These mouthparts have well developed palps but reduced mandibles, which explains the mostly liquid diet of caddisflies.
The larvae are aquatic and begin caterpillar-like. These larvae appear live under a variety of conditions such as ponds, lakes, or streams. They also vary in their habits. After completion of their growth, caddisfly larvae attach their case to something in the water and then pupate within their case. When the pupa is fully developed it chews threw the case and emerges from the water to complete its transformation into adulthood.
Most caddisflies are weak fliers, and in a few species, the female's wings are vestigial (almost non-existent). The eggs are laid near or in the water in large masses. These hatch in a few days, the larvae take a year to develop, and the adults live for about a month. Biologically, caddisflies are important because they serve as food to many fish and aquatic animals.
Links:
Caddisflies (Trichoptera)
(PDF)
Trichoptera (PDF)
Trichoptera
(PDF)
Order Lepidoptera (Lepido=scale, ptera=wing) - Butterflies
The most appreciated of all insects, butterflies and moths comprise the order Lepidoptera. The often beautiful wing patterns seen on these creatures are caused by minute, almost powdery scalse that cover the wings and body. Lepidopterans have four large wings that connected together. They have large compound eyes and long antennae. They have sucking mouthparts with which they suck up liquid food. They coil their long, sucking proboscus when not in use. They have fairly good vision and a larger color range than we have (they see ultra-violet). Butterflies and Moths have a holometabolous metamorphosis. The colored scales are loose and slippery, which allows lepidopterans to sometimes escape predators.
There are several ways to distinguish between a butterfly and a moth. Butterflies have hooked or clubbed antennae while most moths have feathery antennae that taper at the end. Butterfly's front and hind wings are connected by a lobed process at the base of the hind wing which grips the underside of the front wing while moths have a stiff bristle called a frenulum at the base of the hind wing that hooks into the underside of the front wing. Most butterflies are diurnal; most moths are nocturnal.
Adults eat flower nectar for the most part and thus are important pollinators. They also eat decaying fruit juices, manure liquids, tree sap, and secretions from insects (honeydew). Some lepidopterans do not feed at all once they become adults.Females deposit eggs on food plants. The eggs give rise to caterpillars with chewing mouthparts. Caterpillars are eating machines with fleshy projections called prolegs. Prolegs have hooks on the underside that make them stick to surfaces. If a larva has more than five prolegs (and no hooks) than it is not a lepidopteran, it's a sawfly larva (Hymenoptera). Caterpillars may be naked or covered in bristlelike hairs (setae). Typically, caterpillars spin cocoons out of silk and undergo metamorphosis to become adults. Some adult butterflies have no mouthparts because their sole purpose is to reproduce, having eaten as caterpillars.
Links:
Electronic Resources on Lepidoptera
(PDF)
The Butterfly WebSite
(PDF)
A Guide to North American Butterflies
(PDF)
Order Diptera (Di=two, ptera=wings) - Flies
The species in this large order are easily identified because they possess only one pair of wings, which are the front wings. The hind wings have been reduced to small knobs known as halteres. These knobs assist with balance during flight. Flies are both useful and harmful to humans. Many cause disease such as malaria and yellow fever while others are parasites and predators of other insect pests. Diptera have sucking mouthparts that vary greatly between species. Some have piercing mouthparts and in others they are sponging or lapping. The larvae of Diptera are called maggots. Maggots are generally wormlike and legless. They mostly live in aquatic habitats and feed on plants. The adults feed on plant or animal juices such as nectar or blood. Many of these are predacious on other insects.
Links:
Flies and Mosquitoes
(PDF)
Mutant Fruit Flies
(PDF)
Diptera (PDF)
Order Siphonaptera (Siphon=tube, aptera=wings) - Fleas
Fleas are small insects that feed on the blood of birds and mammals. Adult fleas are wingless, laterally flattened, and possess projecting spines and bristles. The antennae are short, they have sucking mouthparts, and long legs with enlarged coxae. Eyes can be present or absent.
Species of fleas are generally restricted to hosts in a particular order or family. About 75% of all fleas are parasites of rodents, 5% of birds, and the rest of other mammals including humans. Species of fleas also differ in their living styles. Some attach to the host only when they are feeding while others spend their entire life attached to their hosts.
Flea eggs vary in appearance and are usually laid on or near the host. They hatch into small, legless, hairy larvae that lack eyes. These larvae are relatively active and feed on organic material that mostly consists of bodily fluid from the host.
Fleas are dangerous because they often carry harmful diseases. For instance, fleas are responsible for the bubonic plague in humans. They also act as an intermediate host for two species of tapeworms. These tapeworm species generally affect dogs and rats, however they occasionally infest humans.
Links:
Flea - Order Siphonaptera
(PDF)
Fleas (Siphonaptera)
(PDF)
Fleas
(PDF)
Fleas
(PDF)
Siphonaptera
(PDF)
Siphonaptera (PDF)
Order Hymenoptera (Hymeno=membrane, ptera=wings) - Bees, Ants and Wasps
Bees, wasps, ants, sawflies, and allies make up Hymenoptera, one of the most interesting insect orders. Hymenopterans exhibit a great amount of diversity and complexity in their habits. Some members have wings, some don't. Those that do have two pairs which are connected to each other by hooks on the margin of the hind wings. The wings have few veins. Ovipositors are often developed into stingers in this species, therefore only females sting. The mouthpats are often mandibulate but in a few higher forms, bees for example, they are specialized tonguelike structures through which liquid food is taken. In many hymenopteran species the members colonize and have highly specialized roles. Workers are sterile females that feed the young and maintain and defend the nest. Only the queen lays eggs and only a few males, who don't tend to live long, ever mate with the queen. Hymenopterans undergo holometabolousdevelopment.pupa may be formed in a cocoon, in the host (for parasitic forms), or in special cells. The gender of all hymenoptera larvae is determined by fertilization. Unfertilized cells become males and fertilized cells become females.
Links:
The Ant
(PDF)
American Apitherapy Society
(PDF)
Wasps
(PDF)
Non-Insect Arthropods Order Information
The following information and list of exemplary links for each non-insect arthropod group was developed by a high school student working on the Bugscope Operations Team.
Try our quick jump list to find what you are looking for faster:
Acari
Araneae
Chilopoda
Decapoda
Diplopoda
Isopoda
Merostomata
Phalangida
Scorpiones
Trilobita
This order (Phylum Arthropoda) encompasses a large group of small to minute animals. These creatures are oval with little or no differentiation between body segments. The larvae (newly hatched young) have three pairs of legs and attain their last pair after their first molt.These creatures are found virtually everywhere in both aquatic and terrestrial areas. Acari are most abundant in the soil where they outnumber other arthropods. Most are predacious and attach to the outside of their vertebrate or invertebrate hosts. Others are scavengers that break down forest litter and some are plant feeders which harm crops. Ticks and Mites are known to be pests to humans as they spread disease. Ticks are larger than most Acari and are parasitic to mammals, birds, and reptiles. They are the most important carrier of disease for animals and are second to mosquitoes for humans. These diseases include Rocky Mountain Spotted Fever and Lyme disease.
Links:
Background Information on the Biology of Ticks
(PDF)
Ticks
(PDF)
Acari - The Mites
(PDF)
Back to Non-Insect Arthropod Order List
Order Araneae - Spiders
Belonging to Phylum Arthropoda, Spiders are a widespread and abundant group. Their bodies consist of the cephalothorax and the abdomen. The cephalothorax supports the eyes, mouthparts, and legs while the abdomen bears the genital structures, spiracles, anus, and spinnerets. Most spiders have eight or fewer eyes and all of them are simple. The number and placement of eyes can be used in identification.
Spiders have poisonous glands which open from the chelicerae. Although all spiders have venomous glands, they are rarely harmful to humans. In fact, only a few species in the United States are considered dangerous. Spiders also have pedipalps which are located behind the chelicerae and are clubbed in male spiders. Spiders have seven-segmented legs and most have two or three claws. Characteristic bristles and hair on the legs is often used in identification. At the end of the abdomen are six fingerlike structures called spinnerets. This is where the silk of the spider is spun. This silk is used to spin webs and create sacs where the eggs are laid.
The females tend to be much larger than the males and in some cases eat the males after mating. All spiders are predacious and eat mainly insects. The victims are generally killed by the injection of poisonous venom.
Links:
Araneae
(PDF)
Araneae, Spiders of North-West Europe
(PDF)
Back to Non-Insect Arthropod Order List
Class Chilopoda - Centipedes
Centipedes, also belonging to Phylum Arthropda, are similar to millipedes. Both are elongate and flattened, however, centipedes have only one pair of legs per body segments and have 15 or more pairs of legs. A centipede's final pair of legs is directed backwards and is different from the other legs. Antennae are long and consist of 14 or more segments. Some centipedes have eyes while others do not. Like millipedes, the centipede mouthparts are mandibles. They have two pairs of maxillae with the second pair appearing leglike. A centipedes fist segment has clawlike appendages that act as poisonous jaws.
Centipedes are generally found in unprotected areas such as in the soil or under logs. They are quick and feed on insects, spiders, and other small animals. They all possess the poisonous jaws which are used to paralyze their prey. Centipedes also overwinter as adults and lay their eggs in the summer.
Links:
Introduction to the Myriapoda
(PDF)
Centipede
(PDF)
Back to Non-Insect Arthropod Order List
Order Decapoda - Crabs, Crayfish, Lobsters, Shrimp
This order of crustaceans contains the most well known members of the crustacean subphylum. Lobsters, crayfish, crabs and shrimp all fall under this category. Members of this order have a carapace, a large fused piece of protective exoskeleton, that covers their entire thorax. They have five pairs of leg-like appendages. The first pair is often actually a pair of claws. Abdomens may be very pronounced (lobsters) or almost non-existent (crabs).
Links:
Fiddler Crabs
(PDF)
Land Crabs of the Saychelles Islands
(PDF)
Lobsters
(PDF)
Spiny Freshwater Crayfish
View as PFD
Back to Non-Insect Arthropod Order List
Class Diplopoda - Millipedes
Belonging to Phylum Arthropoda, Millipedes are long wormlike creatures with many legs. Most have 30 or more legs with most body segments having two pairs per segment. The body, which is cylindrical, has short seven-segmented antennae and compound eyes. Millipede mouthparts are mandibles, and under the mandibles is the characteristic liplike structure: gnathochilarium. This structure is divided into many areas and is often used to identify different millipede groups.
Millipedes generally reside in dark damp places such as in moss, under leaves, and in soil. Some species give off a putrid fluid through openings in the body. This fluid has been found to kill insects when placed in close vicinity to the millipede. While most millipedes are scavengers a few have been found to attack living plants and fewer still are predacious. These creatures overwinter as adults and their eggs are laid during the summer. Baby millipedes begin with only three pairs of legs and gain the others after several molts.
Links:
Introduction to the Myriapoda
(PDF)
Back to Non-Insect Arthropod Order List
Order Isopoda - Pill Bugs, Sow Bugs
These animals are under the phylum crustacea. The most well known member of this order is the pill or sow bug, the little bug that can roll up into a ball. Isopods are dorsoventrally compressed (they're more wide than tall). Though the pill bug is terrestial, most isopods live in the water and have gills on their anterior abdominal appendages. The thoraxes of these animals make up most of the body and usually have 7 pairs of legs.
Links:
Biology of Isopods
(PDF)
Isopoda
(PDF)
Back to Non-Insect Arthropod Order List
Class Merostomata - Horseshoe crabs
Horseshoe crabs (Subphylum Chelicerata) get their subphylum name from the fist pair of appendages which are chelicerae. The rest of the appendages are leglike and function as jaws. Horseshoe crabs have two regions, the cephalothorax and the abdomen. Horseshoe crabs are the marine form of class Merostomata. They are common along the Atlantic Coast from Maine to the gulf of Mexico and can be found in shallow water in sandy or muddy areas. These creatures feed on marine worms and are identified by their oval shell and spinelike tail.
Links:
Horseshoe Crabs
(PDF)
Back to Non-Insect Arthropod Order List
Order Phalangida - Daddy Longlegs, Harvestmen
These arachnid members go by the common names of 'daddy longlegs' or 'harvestmen'. They are not true spiders. One important difference is that phalangids have only one oval shaped body segment. They have two eyes. They have scent glands that secrete a peculiar smelling fluid when disturbed. Some are predators and some are scavengers or plant eaters. Most species live for a year or two.
Links:
Harvestman - Opiliones
(PDF)
Back to Non-Insect Arthropod Order List
Order Scorpiones - Scorpions
These members of the class arachnida are widely known. They have five pairs of legs including two claw like appendages in front. The tail end of the cephalothorax has seven segments and the abdomen has five with a stinger at the end. On the underside of the second segment in the tail there is a pair of comblike structures called pectines whose function is not known. Scorpions have a pair of eyes on their midline (back) and between two and five on their lateral margin. Scorpions are nocturnal and prefer warm, dry climates. They feed on insects and spiders by catching them with their pedipalps (claws) and sometimes stinging as well. A unique feature of scorpions is that their young are born alive, not as eggs. For a period immediately after birth they are carried on the mother's back. It may take several years for a scorpion to reach adult hood.
Links:
Scorpiones
(PDF)
Back to Non-Insect Arthropod Order List
Subphylum Trilobita - Trilobites
This extinct group of arthropods lived in the Paleozoic era. They were flattened like isopods and had three distinct divisions of the body. They had a pair of antennae and their appendages were all similar and leglike.The front of their bodies were covered by a carapace (see Decapods). Trilobites were marine animals.
Links:
Introduction to the Trilobita
(PDF)
Trilobites.com
(PDF)