76 



THE AMEEICAN ENTOMOLOGIST. 



These butterflies occasionally assemble in 

 great numbers. At one time a flight crossed 

 the English channel from France to England, 

 and such was the density and the extent of the 

 cloud formed by the living mass, that the sun 

 was completely obscured for a distance of many 

 hundred yards, from the people on board a ship 

 that was passing underneath this strange cloud. 

 The Potherb Butterfly (Pieris oleracea, Boisd., 

 Fig. 51), is the next species to be described. 



[Fig. 51.] 



Colors — Black and white ; {a) green . 



It has a very wide range, reaching rarely as far 

 south as Pennsylvania, extending eastward to 

 Nova Scotia, and at least as far west as Lake 

 Superior, while in the north it is found as high 

 up as the Great Slave Lake in the Hudson's Bay 

 Company's territory. This butterfly has a black 

 body ; the front wings are white, marked above 

 with black at the base, along the front edge, and 

 at the tip ; the hind wings are white above and 

 lemon-yellow beneath, but without markings 

 except a few black scales at the base. 



About the last of May numerous specimens of 

 this species may be seen over cabbage, radish 

 or turnip beds, or patches of mustard, where, on 

 the underside of the leaves, it deposits its eggs. 

 These are yellowish, nearly pear-shaped, longi- 

 tudinally ribbed, and one-fifteenth of an inch 

 in diameter, and are laid seldom more than two 

 or three together. In a week or ten days the 

 young caterpillars are hatched ; in three weeks 

 more they have attained their full growth, which 

 is an inch and one-half long. Being slender and 

 green (see Fig. 61, a) they are not readily dis- 

 tinguished from the leaves on which they live. 

 They taper a little toward each end, and are 

 densely covered with hairs. They begin to eat 

 indiscriminately on any part of the leaf. When 

 they have completed the feeding stage they quit 

 the plants and re I ii-e beneath palings, etc., where 

 they spin a little tuft of silk, entangle their 

 hindmost feet in it, and then proceed to form a 

 loop to sustain the front part of the body in a 

 horizontal or vertical position. Bending its 

 head on one side the caterpillar fastens to the 



surface, beneath the middle of its body, a silken 

 thread, which it carries across its back and se- 

 cures on the other side, and repeats this opera- 

 tion until a band, or loop, of sulEcient strength 

 is formed. On the next day it casts ofi" the cat- 

 [Fig.52.] ' erpillar skin and becomes a 

 chrysalis (Fig. 62). This is of 

 a pale green and sometimes of 

 a white color, regularly and 

 „ , „ ^.^ finely dotted with black; the 



Colors — Green, white ^ 



and black. sides of the body are angular, 

 the head is surmounted by a conical tubercle, 

 and over the forepart of the body, corresponding 

 to the thorax of the included butterfly, is a 

 thin projection, having in profile some resemb- 

 lance to a Roman nose. The insect remains in 

 this stage for ten or twelve days, when the but- 

 terfly appears. 



In the last of July and first of August, these 

 insects may be seen in large numbers depositing 

 their eggs for a second brood, which wintering 

 in the pupa state, produces the perfect insect the 

 following May. 



This butterfly vai'ies considerably. There are 

 never, we believe, perfectly white specimens, 

 though often nearly so. Again, some specimens 

 have very faint indications of spots arranged as 

 in P. rapm; but on the underside are found the 

 widest limits of variation, for not only do the 

 tips of the front wings become distinctly green- 

 ish, or lemon-yellow, and the veins of that por- 

 tion bordered with grayish scales, but the hind 

 wings may also have the ground color distinctly 

 greenish, lemon-yellow, or whitish, and the 

 veins display gray scales on each side. 



By taking advantage of the habits of these in- 

 sects, they might be nearly exterminated. If 

 boards are placed among the infested plants, 

 about two inches above the ground, the cater- 

 pillars when about to change will resort to them, 

 and there undergo their metamorphoses. They 

 may then be collected by hand on the underside 

 of the boards and destroyed. As the butterflies 

 are slow fliers, they may be taken in a net and 

 killed. A short handle, perhaps four feet long, 

 with a wire hoop and bag-net of muslin or 

 mosquito netting, are all that are required to 

 make this useful implement, the total cost of 

 which need not be more than fifty or seventy- 

 five eents. The titmouse is said to eat the larva3, 

 and should therefore be protected and encour- 

 aged. 



The Soiitliern Cabtage Butterfly. 

 [As the Southern representative of the genus, 

 we will briefiy add an illustrated account of the 

 Southern Cabbage Butterfly {Pieris Protodice, 



