1 88 Psyche [Decemljer 



and sometimes three females have been seen ovipositing at the base 

 of one stem. The hirge number of individuals of this species 

 which appears every j^ear is probably not due to the large number 

 of eggs laid by one female, but to the large number of egg-masses 

 from different females laid in one host. It is not known how 

 many eggs may be laid by one individual, since it has not been 

 found practicable to keep large pieces of the host plant in the 

 laboratory for any considerable length of time. 



Emergence and Development of Nymphs. 



Although the first nymphs do not begin to appear in this 

 locality until early in May, they may be forced in the laboratory 

 earlier than this. The eggs break open widely at the tips but 

 the nymphs sometimes delay emergence for several days after the 

 eggs have begun to open. 



Five instars are passed in the process of development. The 

 first is characterized by the long, fine, hair-like bristles which 

 extend in three rows down both sides of both the thorax and the 

 abdomen, and by the white band down the median dorsal line of 

 the body (Fig. 4). In the second instar (Fig. 5) the lateral 

 bristles hav^e disappeared and the entire body is hairy while the 

 dorsal bristles are simple and long on both thorax and abdomen. 

 The third instar (Fig. 6) shows no dorsal bristles on the thorax 

 and the abdominal bristles are heavy and branched; the pronotum 

 has begun to extend itself posteriorly and the lateral margins of 

 the meso- and metathorax are beginning to form the rudimentary 

 wing-pads. In the fourth instar (Fig. 7) the pronotum covers the 

 •dorsal part of the mesonotum and the wing-pads are well developed, 

 reaching to the second segment of the abdomen. The fifth and 

 last instar (Fig. 8) presents a greatly developed pronotum which 

 now covers both the mesonotum and the metanotum, and the wing- 

 pads are fully formed, reaching to the third abdominal segment. 

 Thus each instar may be recognized by rather clearly defined 

 characters of the thorax and abdomen. 



The time occupied in this process is subject to considerable 

 variation and all of the nymphs from one egg-mass do not reach 

 maturity at the same time, there being sometimes a difference 

 of as much as two weeks between the maturing of the earliest 

 and latest individuals. An average laboratory record shows the 



