of legs are jointed and used for running, climbing, jumping, swimming, digging or grasping. The feelers or antennae are usually threadlike, clubbed, or resemble a feather and extend forward or sidewise from the head. The large eyes are compound, being made up of many great small units which, when magnified, resemble honey-comb. In some cases two or three small bead-like eyes may be present besides the two large eyes. The mouth parts of insects may be formed for chewing, as in the grasshopper, or for sucking up liquids, as in the mosquito. The mouth of an insect is built on an entirely different plan from our own. Chewing insects have an upper and lower lip and between these there are two pairs of grinding jaws. These jaws are hinged at the side of the face and when chewing they come together from either side so as to meet in the middle of the mouth. They therefore work sidewise rather than up and down. The mouth parts of the sucking insects are drawn out to form a sucking tube or proboscis as in case of the butterfly or mosquito.

Leg of grasshopper showing segmentation. The basal segment c, is the coxa, the next t, the trochanter, the large segment f, the femur, the long slender one ti, the tibia, and the three jointed tarsus ta, with claws at the tip.

The internal organs of insects are similar to those of other animals. The digestive tube consists of oesophagus, gizzard, or stomach, and intestines. The nervous system is well developed as shown by the extreme sensitiveness of insects to touch. The brain is comparatively small except in the bees and ants. The circulatory system consists simply of a long tube heart, the blood vessels being absent. In this way the internal organs of the insect are simply bathed in the blood. The system of respiration is most complicated. The air is taken in through pores usually along the side of the body and is then carried through fine tracheal tubes to all parts of the body. You cannot drown an insect by putting its head under water, since it does not breathe through its mouth. The muscular system is similar to that of other animals which have the skeleton on the outside.

The internal organs of the honey bee. Note the strong wing muscles in the thorax. The tube-like heart begins in the head and extends back through the thorax and follows the curve of the abdomen. Below the heart is the digestive tube consisting of the slender oesophagus which extends back to the expanded honey stomach, in which the bee carries the nectar it collects from flowers, then the curled true stomach, the small intestine and expanded large intestine. Below this is the nervous system consisting of the brain and a chain of connected enlargements or ganglia extending back into the abdomen in the lower part of the body. The respiratory system in part appears just above the honey stomach, and the black circular or oval spots are cross sections of connecting air tubes, which run all through the body. Also note the sting with the poison gland and sack which are pulled out with the sting; also the sucking tube for getting honey from flowers, and the structures on the legs for gathering and carrying pollen; the pollen basket is on the back side of the hind leg.

Their Methods of Developing

In most cases the parent insect deposits small eggs which hatch later into the young insects. In some cases, as with the blow-flies, the maggot may hatch from the egg while yet in the parent's body, when the active larva is born alive. Whether the egg hatches before or after it is deposited, the young insect continues to develop in one of three ways. It may resemble the parent and simply grow as does a kitten, or it may look somewhat like its parent though smaller and without wings, as the young grasshopper, or it may bear no resemblance whatever to the parent, as the caterpillar which feeds and grows and finally spins a cocoon in which it passes to the resting chrysalis stage and later emerges with wings. The development of insects is therefore extremely complicated.

The chinch bug showing development with incomplete metamorphosis; a, egg; b, first nymph; c, second nymph; d, third nymph; e, fourth nymph; f, adult winged bug; g, chinch bugs extracting sap from corn plant. To control this pest burn over all winter harboring places and use chemical or dust barriers following wheat harvest.

The Principal Orders

In order to study a group of animals which includes so many thousand different kinds it is necessary to divide them into a number of sharply defined divisions or orders. All animal life is naturally grouped into such divisions and subdivisions. Among the insects we at once detect seven large, sharply defined divisions or orders, and ten or more smaller ones. Of these we have first, the two-winged true flies; second, the four-winged butterflies and moths; third, the hard-backed beetles; fourth, the stinging four-winged wasps and bees; fifth, the variously formed sucking insects or true bugs, as chinch bugs and bed-bugs; sixth, the rapid-flying four-winged snake doctors or dragon-flies and, seventh, the hopping forms, the grasshoppers. Besides these we have the various smaller orders of water-loving insects, fleas, etc. The seven groups mentioned above include the majority of our common forms and in the studies to follow we will include only representatives from these orders.

The Hessian fly showing development with complete metamorphosis; a, egg; b, larva or maggot; c, flax-seed stage; d, pupa; e, adult winged fly; f, wheat stubble with flax-seed stages near base taken after harvest. To control this pest, plow under stubble after harvest; keep down all volunteer wheat and sow wheat after fly-free date in the fall.

Their Habits

The habits of insects are as varied as their forms and adaptations. Some live in the water all their life, others spend a part of their life under water, others live the care-free life of the open air, others enjoy feeding upon and living in the foulest of filth, others associate themselves with certain definite crops or animals thereby doing untold injury, while others produce food and other materials which are to be used by man for his comfort. Every imaginable nook and crook, from the depths of lakes to the tops of mountains, from the warm, sunny south to the cold frigid north, from the foul damp swamps to the heart of our desert lands, offers a home for some small insect.

The most striking habits and developments among insects is found in the more highly advanced families of bees and ants where definite insect societies are formed, resembling in many respects human societies and human activities. Among these villages are established, homes built, battles fought, slaves made, herds kept by shepherds, and even fields cultivated. In these groups we have the