122 



ANIMAL FORMS 



attracted by lights, and have come to be called " electric- 

 light bugs." 



Among our most dreaded insect pests are the chinch- 

 bugssmall black-and-white insects, but traveling in com- 

 panies aggregating many millions. 

 As they go they feed upon the 

 stems and leaves of grain, which 

 they devour with extraordinary ra- 

 pidity. The squash-bug family is 

 also extensive, and destructive to 

 the young squash and pumpkin 

 plants in the early spring. 



The lice are small, curiously 

 shaped bugs, which suck the blood 

 of other animals. The plant-lice, 

 also small, suck the juices of 

 plants, and are often exceedingly 

 destructive. This is especially true 

 of the phylloxera, a plant-louse 

 which causes annually the loss of 

 millions of dollars among the vine- 

 yards of this and other countries. 



Even more destructive are the scale-insects, curiously mod- 

 ified forms, of which the wingless females may be found on 

 almost any fruit-tree and on the plants in conservatories, 

 their bodies covered with a downy, waxy, or other kind of 

 covering, beneath which they remain and lay their eggs, 



119. The flies (Diptera). The group of the Diptera 

 (meaning two-winged) includes the gnats, mosquitoes, fleas, 

 house-flies, horse-flies (Fig. 75), and a vast company of 

 related forms. Only a single pair of wings is present, the 

 second pair being rudimentary or fashioned into short, 

 thread-like appendages known as balancers, though they 

 probably act as sensory organs and are not directly con- 

 cerned with flight. The mouth-parts are adapted for pier- 

 cing and sucking. The eyes, constructed on the same plan 



FIG. 74. Giant water-bug (Ser- 

 phus dilatatus), with eggs at- 

 tached. 



