Insect Biology

Topic 2042

Aaron Gearhart

Biology of Insects

This lecture will go over the following topics

• Insect Body– Head– Thorax– abdomen

• Insect Life Cycles– No metamorphosis– Gradual metamorphosis– Incomplete metamorphosis– Complete metamorphosis

http://www.ent.iastate.edu/list/images.html

Body of an Insect

• Divided into three parts– Head

– Thorax

– Abdomen

Segmentation allows for efficiency since each segment is specialized for a different function

The Head

• Contains the following parts– Eyes – Simple or Compound

– Anennae – used for smelling or feeling

– Mouthparts – for sucking or chewing

www.earthlife.net/insects/six.html

Mouthparts

• Almost infinite variations

• Mouthparts are often used to determine type of control that will be most effective for a specific insect

• Examples:– Fly: has a sponge type mouth– Assasin bug: Has a spear or needle type mouth– Grasshopper: Has a chewing mouth– Some butterflys: Have a long “hose” for sucking nectar

Thorax

• The locomotive segment of an insect

• Contains wings and legs• Of course insects have three

pairs of legs for a total of….6• Insects may have

– 0 wings: ants, lice, mites

– 1 pair of wings: flys, true bugs

– 2 pairs of wings: wasps, bees

http://www.ent.iastate.edu/list/images.html

Abdomen

• Contains the following– Digestive organs– Reproductive organs– Respiratory organs– Excretory organs

Abdomen can change shape depending on how much it ate or if it has eggs.

http://www.denniskunkel.com/PublicHtml/WANTED/BODIES/IndexBodies.html

Lifecycles of the Insect

No metamorphosisGradual metamorphosisIncomplete metamorphosisComplete metamorphosis

No Metamorphosis

• These insects emerge from the eggs looking exactly like the adult but smaller

• Primitive insects like the silverfish are examples of this

• Also known as ametabolous

http://www.life.uiuc.edu/Entomology/insectgifs/thysanura.gif

Gradual Metamorphosis

• Similar to no metamorphosis but the youngster coming out of the egg is slightly different from the adult

• Examples are grasshoppers and crickets

http://www.ent.iastate.edu/

Incomplete metamorphosis

• These insects change from egg -> nymph -> adult

• After their last molt these insects rapidly change to adult

• Some examples would be dragonflies

• Also termed hemimetabolous

http://stephenville.tamu.edu/~fmitchel/dragonfly/photo/cw_aes1.htm

Complete metamorphosis

• Goes through four distinct stages– Egg

– Larvae

– Pupa

– Adult

http://www.geocities.com/pchew_brisbane/wanderer.htm

Questions or Comments?

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