Forms to be looked for on a Field Trip.--Inasmuch as there are over 360,000 different species or kinds of insects, it is evident that it would be a hopeless task for us even to think of recognizing all of them. But we can learn to recognize a few examples of the common forms that might be met on a field trip. In the fields, on grass, or on flowering plants we may count on finding members from six groups or _orders_ of insects. These may be known by the following characters. The order _Hymenoptera_ (membrane wing) to which the bees, wasps, and ants belong is the only insect group the members of which are provided with true stings. This sting is placed in a sheath at the extreme hind end of the abdomen. Other characteristics, which show them to be insects, have been given above. Butterflies or moths will be found hovering over flowers. They belong to the order _Lepidoptera_ (scale wings). This name is given to them because their wings are covered with tiny scales, which fit into little sockets on the wing much as shingles are placed on a roof. The dust which comes off on the fingers when one catches a butterfly is composed of these scales. The wings are always large and usually brightly colored, the legs small, and one pair is often inconspicuous. These insects may be seen to take liquid food through a long tubelike organ, called the _proboscis_, which they keep rolled up under the head when not in use. The young of the butterfly or moth are known as _caterpillars_ and feed on plants by means of a pair of hard jaws. Grasshoppers, found almost everywhere, and crickets, black grasshopper-like insects often found under stones, belong to the order _Orthoptera_ (straight wings). Members of this group may usually be distinguished by their strong, jumping hind legs, by their chewing or biting mouth parts, and by the fact that the hind wings are folded up under the somewhat stiffer front wings. [Illustration: Forms of life to be met on a field trip. _A_, The red-legged locust, one of the _Orthoptera_; _o_, the egg-layer, about natural size. _B_, the honey bee, one of the _Hymenoptera_, about natural size. _C_, a bug, one of the _Hemiptera_, about natural size. _D_, a butterfly, an example of the _Lepidoptera_, slightly reduced. _E_, a house fly, an example of the _Diptera_, about twice natural size. _F_, an orb-weaving spider, about half natural size. (This is not an insect, note the number of legs.) _G_, a beetle, slightly reduced, one of the _Coleoptera_.] Another group of insects sometimes found on flowers in the fall are flies. They belong to the order _Diptera_ (two wings). These insects are usually rather small and have a single pair of gauzy wings. Flies are of much importance to man because certain of their number are disease carriers. Bugs, members of the order _Hemiptera_ (half wings), have a jointed proboscis which points backward between the front legs. They are usually small and may or may not have wings.