38 Annals Entomological Society of America [Vol. V, 
at a time, despite the fact that the anterior part of the body 
was exposed to the air. I sometimes came across forms that 
could not be made to feign death at all, in others again, though 
very rare cases, the feint would be so pronounced that pricking 
the insects only made them more rigid and apparently under 
obligation to serve their time in that attitude. Usually, 
however, a touch with a sharp object makes the nymphs dis- 
continue the feint while a smooth object tends to prolong it. 
Sometimes, before the recovery from a death-feint, the nymphs 
begin to move the sete, or stretch out a limb, and then a quick 
movement of the other limbs follows. Ordinarily, however, 
the recovery is a sudden jerk, and occasionally, if the nymph 
happens to lie ventral side downward, the violent, simultane- 
ous extension of the folded legs throws the nymph into the air. 
Most nymphs can not be made to feign death longer than fifteen 
minutes on a dry table, a fact probably due to the disturbance 
in the metabolism of the body occasioned by the lack of oxygen. 
MOULTING AND LIFE CYCLE. 
The nymphs moult on the average once in about two weeks; 
the intervals being largely independent of the age and size of 
the insect. They grow on the average about one-third of a 
millimeter during the time which elapses between the two suc- 
cessives moults. They do, however, moult several times after 
they are apparently full grown, or when the growth in length at 
least, is not appreciable. The number of moults would probably 
vary during the different seasons if the nymphs were in their 
natural out-of-door environment and the almost regular moult- 
ing may be possibly influenced by the almost invariable tem- 
perature of the water in the aquaria. 
Ten individuals varying from one to nine millimeters, were 
kept in separate dishes with an abundant supply of food; daily 
observations made, and the dates of the various moults recorded 
which are given in the following table. Several of the larger 
forms metamorphosed and some of the small ones died within 
a month or two, and these I was unable to replace on account of 
the rare sizes, but two lived as long as the experiment was 
continued. 
