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Order Coleoptera: Beetles

Beetles belong to the order Coleoptera, it means 'sheath winged', as the front wings are hardened and protect the thin hind wings that are folded underneath and used for flying. One of the key charcateristics shared by the Coleoptera is that the front wings meet in a straight line down the center of the body. They have chewing mouthparts and complete metamorphosis.

The example shown here is a white grub which will become a pupa on its way to emerging from the soil as an adult Japanese beetle. The white grub stage feeds on roots of grasses, while the adult feeds on the leaves, flowers, and fruits of various plants. This is a good example of complete metamorphosis. Note that with complete metamorphosis, there are not wing pads developing on the outside of the larva.

Kentucky Examples in the Order Coleoptera

This is the margined blister beetle. In this photo you can see how the front wings meet in a straight line down the center of the back. Blister beetles get their name from the habit of 'leaking' a caustic fluid from their leg joints when disturbed. In Kentucky, blister beetles can be a problem for hay producers as crushed beetles in the seasoned hay are toxic to horses.

This is a typical tiger beetle. As you can see from the legs, tiger beetles are swift runners and have mandibles to capture prey. Many of the tiger beetle species are brightly colored like this one.

This is a metallic wood boring beetle. These beetles are part of the larger group of wood borers that also includes longhorned beetles. The larvae of these are referred to as flat head borers and commonly leave characteristic 'D' shaped emergence holes in the bark of trees. The borers tunnel in the cambium of the tree and may girdle and kill trees. An accidentally introduced species in this same family is the emerald ash borer which is destroying ash trees in parts of Michigan, Ohio and Indiana.

This is one of the more unusual species in Kentucky, the giant stag beetle. The male (pictured above) has enlarged mandibles which are used to fight other males. Stag beetles are commonly attracted to lights at night near wooded areas.

Weevils, sometimes called snout beetles, have their mouth at the end of a long beak. Although this may appear as sucking mouthparts, the weevil has small, chewing mandibles at the end of the snout. The insect pictured above is the larger chestnut weevil.

This is a lightningbug (note that this is written as one word, because it is not a true bug). Lightningbugs signal among the sexes at night using specific flashing patterns. Light is produced in a special organ at the tip of the abdomen.

The beetle pictured above is a type of longhorned beetle, they are named for the very long antennae. The larvae of many of the longhorned beetles are borers of trees and shrubs.

Updated November 2005


Photo credits:  R. Bessin, Department of Entomology, University of Kentucky; montage created by P. Dillon, Department of Entomology, University of Kentucky


The teaching modules on this site were created by Ric Bessin;
web functionality was created and is maintained by Pat Dillon
Department of Entomology, University of Kentucky, S-225 Agricultural Science Ctr North, Lexington, KY USA  40546-0091.
Please send questions or suggestions to: rbessin@uky.edu OR pdillon@uky.edu