|Beetles belong to the order Coleoptera. The most noticeable way that Coleoptera differ from most other orders is the form and texture of their front wings, but there are also other characteristics that are typical for beetles.|
Various parts of a beetle are described and underlined in the following paragraphs. The descriptions include a little more detail than was given in the previous exercises. Locate and label the underlined parts on the beetle drawings. It would be helpful to have a large beetle to look at while you do this exercise.
Like other insects, beetles have three body regions: head, thorax and abdomen, but the regions are not clearly seen in the top view of a beetle. Remember that wings and legs of insects are always attached to the thorax. In the bottom view of the beetle, you can see the full length of the thorax, which extends from the head to where the hind less are attached. The abdomen is the section after the hind legs. The entire thorax is much longer than the part you can see in top view. The only part of the thorax visible in the top view is the pronotum, or top of the first thoracic segment.
Typical beetles have two pairs of wings, but the front pair, called elytra (plural of elytron) are stiff and not used for flying. When a beetle is not flying the elytra meet each other in a straight line as they lie over the back, and the hind wings are folded and hidden under the elytra. In most beetles, the elytra are long and cover the abdomen. In some beetles the elytra are short and most of the abdomen can be seen when viewed from the top. These beetles resemble earwigs (Order Dermaptera) in appearance except that earwigs have pincers at the end of their bodies.
The jointed legs of insects are composed of five main segments. Beginning with the segment nearest to the body they are: coxa, trochanter, femur, tibia, and tarsus. The femur is usually the biggest segment. The trochanter is often very small and hard to see. The tarsus is divided into a series of subsegments, and the last tarsal subsegment bears claws. The number and shape of tarsal subsegments are important characteristics for identifying different beetles.
On the head of a beetle, the compound eyes and antennae (feelers) are usually easy to see. There are many forms of antennae among the beetles. Some antennae are short, clubbed, comb- like or even hidden in pockets. The mouthparts of beetles are jaws adapted for chewing or biting. They never have sucking beaks such as you have seen with the true bugs (Order Hemiptera). However, some beetles have long slender snouts with small jaws at the end of the snout. Attached to the beetle's mouthparts are short feeler-like palps. The palps act like fingers to handle the beetle's food while it is eating it. Most other types of insects with chewing mouthparts also have palps.
Labeling the Beetle Exercise
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