122 FIRST LESSONS IN ZOOLOGY. 



Most caterpillars are more or less hairy or spiny, ren. 

 dering them, when especially so, disagreeable to birds j be- 

 sides this, they are bright-colored, so that birds readily rec- 

 ognize them and waste no time over them, but search for 

 the common green smooth-bodied ones, which are, however, 

 so difficult of detection by the birds that plenty are left to 

 become moths or butterflies. Certain caterpillars, as the 

 currant-worm, .though smooth-bodied, are brightly spotted; 

 these, however, the birds find, have a disagreeable taste. 

 The bright colors are thus danger-signals, warning off the 

 birds. 



We will now suppose that the caterpillar has got its 

 growth, and is about to change to a chrysalis. When fully 

 fed the caterpillar stops eating, and in a day or two throws 

 off the caterpillar's skin and becomes a pupa or chrysalis. 

 The latter word is derived from the Greek, meaning golden, 

 in allusion to the golden spots which adorn the chrysalids 

 of some butterflies. Our Tumus caterpillar, before pupa- 

 tion, as the act of becoming a pupa may be called, becomes 

 thick, and the head is drawn in. It spins a loose open-work 

 platform of silk on the under side of a leaf; its tail is firmly 

 anchored in the mass of silk by certain hooks at the end, and 

 meanwhile it throws around its body near the head a strong 

 silken cord as a support. Our Tumus chrysalis is not bright- 

 colored, but allied in color to a dry leaf or piece of wood, 

 so as to be easily overlooked by birds. Here it remains 

 through the winter until the end of the succeeding May or 

 first of June, when the butterfly within, which has been 

 growing rapidly during the preceding warm days, by its 

 convulsive struggles bursts the pupal skin on the back, 

 forcing the covering of the head and mouth-parts aside, and 

 draws itself out of the rent. It stands on its feet for a few 

 minutes, while its wings expand, and then takes flight and 

 sails gracefully on its broad wings through the air. 



While there is great uniformity in the shape of the body 

 of butterflies and moths, their habits are, within narrow 

 limits, quite diverse. Some fly by day, others at dusk, 



