THE BUTTERFLIES AND MOTHS 63 



Giant Silkworm Moths. We have several large moths in 

 the United States, expanding from ten to fifteen centimeters 

 (four to six inches), whose larvae spin silken cocoons, some 

 of which have been utilized to a limited extent by man. 

 They are magnificent insects, with broad wings beautifully 

 colored, and with large feather-like antennae. The antennae 

 of the male are much larger than those of the female. Even 

 in crowded cities the gorgeous brown and red cecropia is 

 not uncommon, while the polyphemus, luna, and promethea 

 are species of especial delight to those who love the beauti- 

 ful. The larvae feed on the leaves of forest and fruit trees 

 and are more or less armed with a variety of colored spines 

 and tubercles. The caterpillars, like other larvae which feed 

 upon plant food, are remarkable for the amount of food 

 which they consume and the great increase in size in early 

 life. The caterpillar of the American silkworm moth 

 (Te'lea polyphe' mus) , which weighs on hatching one twen- 

 tieth of a grain, increases to ten times its weight within ten 

 days, and to over four thousand times its weight in fifty 

 days. By this time it has consumed over one hundred oak 

 leaves, weighing almost three quarters of a pound, and 

 drunk nearly one half an ounce of water. The larvae of these 

 moths spin conspicuous brown cocoons, which can easily 

 be collected in the winter from the branches and leaves of 

 trees to which they are attached. In the spring the imagoes 

 escape from one end of the cocoons by cutting the silk with 

 a pair of stout spines, one on each side of the thorax, at the 

 base of the anterior wings. 



Underwings. A very striking group of moths is the under- 

 wings {Catoc'ala), which have the anterior wings in sober 

 tints of brown or gray, but the posterior wings black with 

 broad markings of red or yellow. When at rest the pos- 

 terior wings are covered, and the moth tends to be protec- 

 tively colored; but when in flight the broad, contrasting 



