

222 THE INSECTS— ARTHROPODS 



that remains for quite some time and often a delicious looking- berry will 

 have a most disagreeable taste due to its prior contact with a stink bug. 

 The monarch butterfly probably looks as if it would taste good to a bird, 

 but birds only attempt to eat one ; after that the monarch is safe because 

 of its bitter taste. The blister beetles have blood that will irritate and 

 raise a blister on the skin of any animal that crushes them. 



A final method of protection that might be mentioned is protective 

 mimicry. Insects develop body shapes and colors that so closely re- 

 semble their surroundings that detection by sight is very difficult. A 

 tomato worm may be on a tomato plant and give evidence of its presence 

 by damage done in feeding, yet a careful examination of the plant may 

 fail to reveal it even though it is two or three inches long. Some butter- 

 flies look so much like leaves that they are indistinguishable from them 

 when at rest. Walking sticks look very much like twigs and assume 

 poses identical with the appearance of the twig which they are on. Some 

 caterpillars have spots which appear as two great eyes on their back, 

 which gives them a forbidding appearance. Some insects appear to 

 take advantage of protective adaptations of other insects by mimicking 

 them. The viceroy butterfly is marked very much like the monarch 

 butterfly and it is thought to be let alone by birds who have tried to eat 

 the bitter-flavored monarch. 



Insect Voices 



When we hear the loud singing of the cicada, the chirping of the 

 cricket, and the buzzing of the bees, we might get the impression that 

 insects are a noisy group of animals, but the great majority of them are 

 mute. None of them have anything like vocal cords that vibrate when 

 air is expelled from their bodies so there are other devices present for 

 sound production in those few that make sounds. One of the most com- 

 mon methods is the scraping of the wing covers or legs. Male crickets 

 scrape their wing covers continuously to produce their singing or strum 

 them to produce the chirping. It is said that the timing of the chirps 

 of a tree cricket is in direct relation to temperature and that the tempera- 

 ture can be ascertained by counting the number of chirps per minute. 

 The katydids also use their wing covers and produce a sound resembling 

 their name. Male grasshoppers, during the mating season, fly in the air 

 above the females, clicking their wing covers together like castanets to 

 produce a very characteristic sound. 



The cicadas, also called seventeen-year locusts or dog-day harvest 

 flies, climb trees in the summer and produce a lonesome continuous sing- 

 ing that can be heard at a great distance. These insects have a cavity 



