186 Psyche [December 



the latter part of the season the males are more numerous than 

 the females — counts made in late September 1911 showed an 

 average of five to one — and this condition has been regularly 

 observed each year. It is of interest to note that the opposite 

 is true of Thelia bimaculata, the other species inhabitating the 

 locust, in which species the males become scarcer in August and 

 have practically disappeared by the first of October, although the 

 females persist as do the males of Vandiizea arquata. There is no 

 evidence to show that adults survive during the winter. Careful 

 examination has failed to show any trace of their hibernation and 

 no adults have been observed in the spring previous to the de^'elop- 

 ment of the nymphs. 



Nymphs appear locally about the first of May, the earliest 

 field record of their presence being April 26, 1914. They are 

 usually found flattened in the crotch of a twig or axil of a leaf, 

 generally just above the egg-mass from which they hatched. 

 The most usual position shows the head pointing toward the angle 

 in the stem and the body tightly compressed into a crevice in the 

 bark. Their protective resemblance wliile in this position is 

 excellent and were it not for the attendant ants, the presence of 

 the early stages of the nymphs would escape any but the most 

 careful search. Like most Membracid nymphs which give off an 

 anal liquid, this liquid is excreted when the nymph is picked up 

 or disturbed. The immature forms are very sluggish and merely 

 hold fast to the irregularities of the bark when an attempt is 

 made to remove them. They seldom move more than a few inches 

 from the egg-slit until the last instar, at which time they crawl 

 out to the under-side of a leaflet for the last molt. 



Nymphs have been collected in the first and second instars 

 late in October, and it is probable that many of the last brood 

 fail to reach maturity in years in which there is early frost or 

 premature cold weather. 



Mating and Oviposition. 



Mating begins in the field during the middle of June. The 

 earliest rec6rded date is June 12, 1911. The pair is usualh^ found 

 in the mass of individuals in the angles of the branches. They 

 seem quite restless at this time and are easily disturbed. When 

 molested they fall to the ground, not. however, becoming detached 



