THE CONCHUELA. 41 



none surviving after tlie fourth day. There seems to be httle or no 

 difference in the abihty of nymphs in later instars to withstand 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 

 fine 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. 



Nymphs, 

 feeding and gregariousness. 



For several hours after hatching, the young nymphs of the con- 

 chuela remain closely clustered either on or near by the egg-batch. 

 If there are any unhatched eggs in the batch, the nymphs after a 

 few hours' quiescence begin to feed 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 of a batch 

 to enable several nymphs to molt for the first time. For the most 



