TWO INSECTS OF THE ORCHARD — SNODGRASS. 497 



specially abundant during the summer, the cocoons often lie close 

 together or may be even massed against one another. When newly 

 made each cocoon is hedged about by a bristling palisade of silken 

 spikes, 25 or 30 of them, standing erect in an oval about its long axis 

 (pi. 3, H). But these delicate threads are soon broken off or beaten 

 down by the wind and rain till little evidence of them remains. 



If we would interview the occupant of one of these fluted wigwams 

 we must break in by force, for there is neither door nor other en- 

 trance ; and, once in, we are likely to find that the owner is asleep, 

 already in the chrysalis or pupa stage, and therefore in no condition 

 to give us much information. However, though we can learn little at 

 this season of the creature that made the house, the structure of the 

 dwelling itself is well worth a study. Its form (fig. 8) is not en- 

 tirely symmetrical, one end being slightly thicker than the other and 

 tapering more abruptly, unless the other happens to abut against 

 some projection of the bark, as it frequently does, when it may be cut 

 off square. There are usually seven of the lengthwise ribs, one median 

 and three on each side, though the uppermost pair, those nearest the 

 foundation, are 

 sometimes lacking. 

 The tapering ends 

 are made of thin- 

 ner material than FlG- ^' — Cocoon of Bucculatrix pomifolieUa, the Ribbed-Cocoon- 



Maker of the apple (enlarged 10 times). 



the middle part, 



and, in the larger end, the edges of several sloping, crosswise parti- 

 tions are faintly visible. There are usually three of these but the 

 number varies from one to four. 



The walls of the cocoon consist of two layers (pi. 3, F and G), a 

 thick outer sheathing (r) in which lengthwise thickenings form the 

 ribs, and a smooth inside lining (d) which has a different texture and 

 is of a pale yellowish tint. The outer sheath is securely attached to 

 the support all around the base line, while the inner layer forms a 

 complete capsule within the shelter of the other. The interior is di- 

 vided into a main chamber (e) and several antechambers bjr the cross- 

 wise partitions (/) above noted. The main compartment (e) is a 

 snug little room, well lined with silk, about two-thirds the total 

 length of the outer cocoon. It is occupied by the pupa (g) which 

 lies on its stomach with its head just behind the rearmost of the 

 front partitions. Tucked away in a wad at the rear end of the cham- 

 ber is the cast-off skin of the caterpillar that built the cocoon and 

 inclosed itself in the pupal compartment, then shedding its working 

 clothes and assuming the pupal form for the long winter rest. 



The Bucculatrix pupa is a compact, cylindrical chrysalis, about 

 one-eighth of an inch in length, of a dark reddish or purplish-brown 

 42803°— 22 32 



