THE CONCHUELA. 41 
none surviving after the fourth day. There seems to be little or no 
difference in the ability of nymphs in later instars to wit hai and starva- 
tion, so far as observed in all cases with summer temperatures, death 
taking place in from 2 to 4 days. Data in connection with the retard- 
ing influence of cold, given in the preceding paragraph, illustrate the 
effect of low temperature on the length of life without food of nymphs 
in the fifth instar. In an ice box with an average temperature of 
48.6° F., the life of a nymph of the first instar has been prolonged to 
nearly 40 days without food. In the brood of 24 nymphs to which 
this specimen belonged, all were alive on the seventeenth day after 
being placed in the ice box; 18 alive on the twenty-third day; 10 
alive on the twenty-ninth day ; and only 1 alive on the thirty-seventh 
day. A third-instar nymph, robust, and apparently well fed 
previously, lived only 8 days in the ice box without food, the 
temperature as before averaging 48.6° F. 
As the time for molting approaches, a nymph becomes less active, 
ceases to feed, and shows a tendency to seclude itself where it will be 
less liable to interference by other individuals of the brood. A twig 
or other suitable object is tightly clasped, and the insect by pressure, 
exerted perhaps by means of air drawn into the trachea, splits the 
integument of the dorsum along the mesal line of the thorax, and in a 
line on each side of the head extending from the inner margin of the 
eye backward to the prothorax. The insect becomes freed from its 
old skin usually in the course of twenty or thirty minutes, although 
in one observation a conchuela in molting its fifth-instar skin required 
slightly over an hour. The insect as it emerges is pale pink and very 
soft, but gradually attains its normal color during the course of an 
hour. Adults remain soft to the touch for several days after molting. 
The molted skin which originally covered the abdomen shrivels, and, 
as is also the case with the integument which covered the thorax and 
head, only the black markings remain. 
HABITS. 
\ N MIMIS. 
FEEDING AM) GREGARIOUSNESS. 
For several hours after hatching, the young nymphs o( the con- 
chuela remain closely clustered either on or near by the egg-hatch. 
If there are any unhatched eggs in the batch, the nymphs after a 
few hours' quiescence begin to (vod on them, although it is probable 
that if such eggs contain nymphs they are dead or unable to hatch. 
Frequently enough food is contained in unhatched eggs o( a hatch 
to enable several nymphs to molt for the first time. For the most 
