PIERINAE: PIERIS OLERACKA. 1201 



Having completed its skein of tlireads, tlic larva straightens itself, and it is then 

 noticed tliat abont two-thirds of its length is forward of tlie skein. It now l)Ccomes 

 qniot and motionless, bnt its body gradually contracts in length, wliereby, at the end 

 of an hour or two, its anterior part is found to l)e but half as long as it previously 

 was, the skein now girting it around its middle. It has also undergone a sensible 

 change in its form, that portion which is forward of the girt being thicker and cylin- 

 drical, whilst that which is back of it is gently tapered. 



The larva remains in this position, with its hind feet fastened into the little hillock 

 of silk threads at the end of its body and the loop around its middle, from twenty to 

 thirty honrs. Then, with some writliings and contortions, a cleft is opened in the 

 skin on the upper side of its neck, which crack soon extends along the middle of the 

 head and the fore part of the back, forming an oi-iflce of sullieieut size to allow the 

 body to pass out through it, and when the head is also disengaged, it rests upon the 

 old skin of the larva. The pupa now, by contracting and elongating itself, rapidly 

 crowds the skin backward, crumpling it together underneath its loody, until only the 

 conical hind part remains upon the pupa. Being securely lield by the loop of silk which is 

 now around it, the pupa readily -withdraws the tapering hind end of its body from the 

 remainder of the larva skin, and the tip of its body being furnished [on the] under 

 side with a number of minute hooks, it pushes these backward beyond the shriveled 

 remains of tlie larva skin, and fastens them into the little wad of silk threads to which 

 the larva skin is also attached by the minute hooks of the hind feet. This larva skis, 

 being now a crumpled mass of membrane and hairs, discommodes the pupa by being 

 crowded as it is under and around the hind end of its body. In order to remove it, 

 therefore, the end of its body being bent into a curve at this time and fastened at its 

 tip, it moves this part of its body around and around, in a rotary manner as it were, 

 thus crowding against the pellet of old skin, dislodging it from its former place, and 

 gradually breaking it off from its connection with the little bundle of silk threads. It 

 continues this motion some little space of time, to accomplish this purpose — -over a 

 half minute, I should judge it to have been, in the instance which I witnessed. At 

 length the crumpled mass, having become rolled into a little wad no larger than a ker- 

 nel of allspice, becomes entirely detached and falls to the ground. 



As yet the pupa retains the shape of the larva, being thickest anteriorly and grad- 

 ually tapered to the tip, without any angular projections upon the back, only the horn 

 at the anterior end and the wing sheaths having their pupa development. But the protu- 

 berance upon the back of the thorax case soon begins to appear, and shortly after this 

 a slight angular projection becomes perceptible upon each side of the middle of the 

 back. These gradually become more prominent, and in a short time the whole sur- 

 face becomes molded into its normal pupa form. (Rep. ins. N. Y.. xiii : o36-.538.) 



Gosse once found one "bound in a perpendicular position head down- 

 ward to an upright post." The girt, which in the chrysalis is always found 

 in the middle of tiie first abdominal segment, is in the caterpillar before 

 pupation found either in the middle of the same segment or in the incision 

 betweoii it and the second. 



Life history. This butterfiy, which appears to be generally triple 

 brooded, passes the winter in the chrysalis ; the first brood has been seen 

 as early as April 18, but usually appears between April 27, and May 9, 

 a week or thereabouts after P. rapae. For several years Fitch observed 

 it at East Greenwich, N. Y., for tlie first time on May 8 and 9 and only 

 once as early as May 6 ; in northern localities it is sometimes as late as 

 the third week in .May. It usually becomes abundant between the 10th 

 and 15th of the month and continues until the end of the first week in 



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