Wheel BugMore than 100,000 species of insects are found almosteverywhere in North America, but very few are harmful.Insects are important to the food chain, pollination, honey, wax,shellac, silk, food, scavenging, and decomposing.
Lady beetle adult and larva - good or bad?Lets examine which insects are "good" and which ones are"bad". Are lady beetles good or bad? Well, they are good whenthey eat aphids, but bad when hundreds collect inside yourhouse.
Honey bees - good or bad? Jim Kalish Dept. of Entomology, University of Nebraska-LincolnAre honey bees good or bad? They are good whenthey pollinate and produce honey, but bad when they sting.
• Kingdom In school we learned that animals are divided into• Phylum smaller and smaller groups. Lets look where• Class insects fit in the animal kingdom. From top to• Order bottom, each category has fewer species, and the• Family groups of animals within each category are• Genus increasingly similar.• species
Using the house fly as an example. Notice the• Kingdom- animal genus and species is the official scientific• Phylum - arthropod name of the animal. This name is valid in• Class - insect any country of the world and is an• Order - diptera important way to avoid confusion. This two-word Latin• Family - muscidae naming system was developed in 1758 and• Genus - Musca has hardly changed since then. There are• species - domestica some important things to know about it.
House Fly Musca = fly domestica = homeScientific names are always two words. The first part of the name(Genus) is always capitalized. This lets us know that it is the genus.The second name is always in lower case and is usually descriptive ofthe insect in some manner. Because these words are in Latin, they arealways italicized (or underlined which substitutes for italics).
Interesting Scientific NamesEubetia bigaulae Brown (tortricid moth)
Insects also have common names.One problem with common names is that there may be morethan one common name for the same insect. Commonnames often differ between geographical regions. Do youknow what a skeeter hawk is? Or a cow killer? Did youknow a velvet ant really is not an ant, but a winglesswasp? ...and locusts are really a type of grasshopper - not acicada.
Skeeter Hawk Cow Killer Velvet ant Cicada Locust Locust
Important rules govern the use of common names. If the insect trulybelongs to the group that the name denotes, then the common name shouldbe two words. For example, a honey bee is a true member of the bees, sohoney bee (or bumble bee) is always spelled as two words despite whatyour common dictionary may print. honey bee bumble bee honeybee
Which of the following should be two words?• butterfly • whitefly• dragonfly • damselfly• horsefly • fruitfly• housefly • mayfly
Only these insects are true flies• butterfly • whitefly• dragonfly • damselfly• horse fly • fruit fly• house fly • mayfly
External AnatomyAdult insects are known for having three major body regions,six legs, one pair of antennae and usually two pair of wings asadults. head thorax abdomen
Adult insects develop as a composite of fused segmentswith specific body part associations. from the 1995 Physiology or Medicine Nobel Poster
antennae compound eyesThe first bodyregion is the head. HEAD headInsect heads can behighly variable, butmost possess eyes,antennae andmouthparts. mouthparts
Antennaebeetle butterfly fly ant termite June beetleAntennae are used by insects as major sensorydevices, especially for smell, and can be adaptive for theinsect in many ways.
Two Examples of Mouthpartschewing piercing/suckingInsect mouthparts are also highly modified for theinsect. Chewing, biting, or sucking, are a few examples.Mouthparts of an immature insect may differ from those ofthe same insect in its adult stage.
Picture of bodypartsThe middle body region iscalled the thorax and iscomposed of three fused Thoraxsegments. All legs andwings are located on thethorax.
digging swimming suction grasping Like the mouthparts and Legs antennae, insect legs are quite variable in form and function and reflect the insects lifestyle.
The last body region iscalled the abdomen. It iscomposed of many segmentsconnected by flexible Abdomensections allowing it greatmovement.
Insects possess an exterior covering called theexoskeleton. They do not have internal bones. Thissegmented "shell" is what gives insects shape and canbe very hard in some insects. It is often covered with awaxy layer and may have "hairs" called setae.
Internal AnatomyInside the insect we find the systems for respiration,circulation, nerves, and digestion, but there is littleresemblance to the same systems found in man or othermammals.
Digestive System foregut hindgut Digestive sys midgutThe digestive system is a tube that opens at the mouth and empties atthe tail end of the insect. It is divided into three parts called theforegut, midgut, and hind gut. In some insects such as the honey bee,the foregut acts as a crop to carry or hold liquids which can beregurgitated later.
Circulatory System “ heart ” aortic pumps Circ systemThe circulatory system is not composed of a central heart, veins andarteries which circulate blood cells and transport oxygen. The insectcirculatory system is a simple tube down the back which is open at bothends and slowly pulses body fluids and nutrients from the rear of theinsect to the head.
Insects have a less centralized nervous system than humans. The nervechord runs along the ventral or bottom aspect of an insect. The brain isdivided into two main parts. The largest lobes control important areassuch as the eyes, antennae, and mouthparts. Other major concentrationsof nerve bundles called ganglia occur along the nerve chord and usuallycontrol those body functions closest to it. two lobed brain Nervous system nerve bundles (ganglia) Nervous System
The respiratory system is composed of air sacs and tubescalled tracheae. Air enters the tubes through a series ofopenings called spiracles found along the sides of the body.The largest spiracles are usually found on the thorax wheregreater musculature from wings and legs require moreoxygen. There are no spiracles on the head.
Life CyclesThe many diverse orders of insects have four different types of life cycles.These life cycles are called "metamorphosis" because of the changes ofshape that the insects undergo during development.
Without Metamorphosisegg nymphs adult Without meta The first type is "without" metamorphosis which the wingless primitive orders such as silverfish (Thysanura) and springtails (Collembola) possess. The young resemble adults except for size.
Incomplete Metamorphosis egg naiads adult Incomplete metaThe second type is "incomplete" metamorphosiswhich is found among the aquatic insect orders such asmayflies (Ephemeroptera) and dragonflies (Odonata).
Gradual MetamorphosisThe third type is "gradual" metamorphosis seen in such orders as thegrasshoppers (Orthoptera), termites (Isoptera), thrips (Thysanoptera),and true bugs (Hemiptera). This life cycle starts as an egg, but eachgrowth, or nymphal stage looks similar, except it lacks wings and thereproductive capacity that the adult possesses. Gradual metaegg nymphs adult
Complete Metamorphosis The fourth type is "complete" metamorphosis found in butterflies (Lepidoptera), beetles (Coleoptera), flies (Diptera), and bees, wasps, and ants (Hymenoptera). This life cycle has the four stages of egg, larva, pupa, and adult. Each stage is quite distinct.egg larvae pupa adult
It should be noted that because insects are hard-bodied,they cannot grow larger gradually. Instead they growlarger in steps by shedding the hard exoskeleton for abrief period of expansion. The brief periods between orwithin stages are called molts. Insects are soft-bodiedand vulnerable during this time. recently molted roach
Today weve discussed what makes an animal aninsect and the main characteristics of an insect.Hopefully you will have a better understandingof how insects fit into our environment and whyClark Jack Kellythey do some of the things they do.
Prepared by Stephen B. Bambara Extension Entomologist NC STATE UNIVERSITYCopyright 2001