PIERINAE: EURYMUS PIIILODICE. 1121 



ural variation. It has also Ijeeu t'ound upon wild lupine, Lupinus perennis 

 L., lucerne, Medicago sativa Linn., other species of Medicago, the ground 

 plum, Astragalus caryocarpus Ker, and cultivated pea, Pisum sativum 

 Linn. I saw a female lay three or four eggs on a single clump of Vicia 

 cracca Linn., and Fletcher reports that the caterpillars were destructive a 

 year ago to the leguminous plants in the seed beds of the experimental 

 farm in Ottawa, "species of Cytisus, Caragana and allied plants having 

 to be constantly watched and kept clean by the use of hellebore and 

 pyrethrum." Mr. Angus also found an egg on a blade of common grass, 

 and I have seen one also (laid upon the upper surface), but the caterpil- 

 lar is not known to feed upon it. 



Habits of the caterpillar. The escaping larva eats a iiole out of the 

 side of the egg, a little below the summit, and afterwards eats a portion 

 more, but, in captivity at least, it does not devour much, never the whole 

 of the egg. The young larvae, says Edwards, "are at first rather diffi- 

 cult to manage, having a disposition to roll off the leaves, and are apt to 

 be lost in the breeding cage. . . . This tendency to drop at the least dis- 

 turbance the larvae retain till maturity, and it is naturally their sufficient 

 protection against enemies or destruction." The young caterpillar rests 

 upon the midrib of the leaf, more commonly upon the upper surface, with 

 its head indifferently toward the base or the apex of the leaf, and in this 

 position, after the first change of skin, can scarcely be seen, so closely 

 does its color resemljle that of the plant. "When first from the egg, 

 each makes for itself a hole in the leaf, and feeds at the edges of this for 

 several days" (Edwards). It devours all but the principal veins, often 

 commencing at the tip, so that when it has reached the base, only the 

 skeleton remains ; later it devours the entire leaf. In the final stage, 

 after eating, it rests upon a stalk, with the first two pair of true legs 

 raised from the surface and extended forward. It feeds rather rapidly, 

 sometimes attaining maturity (in New England) in about three weeks ; 

 its first stage then only lasts two days : the second four or five, and the 

 subsequent stages progressively longer. 



Pupation. Edwards gives the following account of its changes : — 



As the time approaches for the change to chrysalis, the larva seeks the protection of 

 some stem, bit of bark, or fence rail, spins a button of pink silk and a light web over 

 the surface of the object, fastens its anal feet in the one and its fore feet in the other, 

 and hangs with its back curved downward or outward. Gradually the markings of 

 the body become obliterated, lost in uniform green. In this condition the larva rests 

 for some hours, then rousing itself, spins a loop of several threads from the base of 

 the feet on one side to a like point on the other, instinctively knowing just how long 

 to make the threads, and presently, seizing the loop in its jaws, manages to throw it 

 partly over the head, and by a great effort works it entirely over and down the back to 

 the fourth segment, and stops exhausted. Some hours pass without any motion, when 

 suddenly the skin splits on the back of the anterior segments and is rapidly shuffled 

 off, exposing the chrysalis, which rests secure on its girdle of silk. (Butt. N. A., il: 

 Colia.s ii, iii.) 



141 



