38 PLANT-BUGS INJURIOUS TO COTTON BOLLS. 
female brought from the field into the laboratory proved unfertilized; 
hence this factor should be eliminated from the laboratory records 
in order to make them comparable with actual field conditions. 
As an illustration of the mechanical prevention of hatching referred 
to, a conchuela in one instance deposited eggs in two layers, the 
nymphs in the lower layer of eggs, numbering 20, being of course 
unable to escape from the shells. This manner of depositing the 
eggs was evidently due either to interference by other specimens in 
the cage or to a lack of sufficient leaf-area, both of which conditions 
are abnormal. Occasionally eggs are deposited, both in the labora- 
tory and in the field, wrong side up with relation to other eggs of the 
batch. This also usually results in mechanical prevention of hatching 
and accounts for the failure to hatch of somewhat less than 1 per cent 
of the 942 eggs referred to above. Other eggs may fail to hatch 
owing to the exit hole at the top being abnormally small, as the 
author has observed to occur in two instances with eggs of the harle- 
quin cabbage bug (Murgantia Mstrionica Halm). The extent of 
this abnormal condition may not be noticeable, yet sufficient to 
prevent emergence of the nymph. Still other eggs may be abnormal 
in the respect that the lid which must be raised to permit the escape 
of the nymph is too solidly attached to the neck of the egg in 
proportion to the strength of the insect. 
EFFECT OF LOW TEMPERATURE ON VITALITY. 
An experiment was made to determine the extent to which de- 
velopment of eggs might be retarded or otherwise affected by low 
temperature. In this experiment 12 egg-batches comprising 288 
eggs were used, all of which were deposited between August 27 and 
September 16 by 8 different females. Each batch of eggs was 
placed in an ice box within 24 hours after being deposited and kept 
there until November 2, with the temperature almost invariable and 
averaging 49° F. Upon examination it was found that the eggs had 
been entirely destroyed, being shriveled so that there could be no 
doubt of their condition. It would seem, therefore, that such long- 
continued low temperatures are fatal to the conchuela in the egg-stage. 
HATCHING. 
As the eggshell is nontransparent, the developing nymph is invisible 
up to the time of hatching. The stout spine on the egg-burster is 
directed at the suture between the lid and the neck of the egg at a 
point opposite the hinge. By pressure from below a split is made 
along the suture and the pale pinkish head of the nymph surmounted 
by the egg-burster appears beneath the partially opened lid. The 
integument of the insect being soft, the emergence is by slow, scarcely 
perceptible peristaltic movements, the egg-burster slipping over the 
