the concb i;i;la. 39 
head and along the venter as the emergence progresses. The position 
of the nymph in the egg is with the dorsum toward the binge of the 
lid. The antennae and legs are closely appressed to the body and 
extended directly backward. Movement of the antenna and legs 
begins as soon as they are free from the egg and emergence is not 
completed until the legs are sufficiently strong to enable the insect to 
cling to the egg-batch. Individual nymphs have been observed to 
emerge in from 12 to 15 minutes after the lid is first raised. Emer- 
gence of nymphs from a batch of eggs usually extends over a period 
of less than labours, but activities in this line as in others are largely 
under the influence of temperature. A record on October 10 shows a 
difference of 2 hours and 15 minutes between the appearance of the 
first nymphs and last nymphs to emerge from a batch of 13 eggs. 
Xy.mphs. 
duration" of xymphal stages. 
Under normal summer temperatures. — In spite of the most careful 
attention one can reasonably give, the death rate of Pentatomid 
nymphs under observation in the laboratory is very high. In no 
case were nymphs of the conchuela reared to maturity in the labora- 
tory, but the duration of the various stages was determined by more 
than 35 individual records. The prevailing temperature conditions 
seem to control the duration of the nymphal stages of these and other 
Pentatomids, while a lack of food supply seems to result only in either 
a stunted growth or death from starvation. During the months of 
July and August, 1905, at Tlahualilo, Durango, Mexico, and Dallas, 
Tex., respectively, the data summarized in the following table were 
obtained, being based on from 5 to 35 specimens in each instar. 
Table XVI. — Observations on duration of nymphal stages of the conchuela. 
Stage. 
Average Minimum Maximum 
duration, duration, duration. 
Days. Day*. 
First instar 4.:. 4 5 
Second instar 6 7 
Third instar s 10 
Fourth instar S ."> 12 
Fifth instar 
All nymphal instars 
It is very unlikely that the maximum duration of each stage given 
above would ever be equaled by a single specimen passing through the 
successive stages, even in the laboratory during the summer months. 
It is, moreover, probable that under out-of-door temperature condi- 
tions the average duration of all nymphal instars taken together is a 
few days less than the average obtained by the laboratory observations. 
