62 Trans. Acad. Sci. of St. Louis 
with show that the length of time between the emergence 
of the young and the death of the parents was very brief 
and sometimes reduced to nothing. 
There is strong dissimilarity between the sexes of the 
adult roach, the female having only rudimentary wings 
(see fig. 1). In the nymph stage it is hardly possible 
to distinguish the sexes. The roach reaches the adult 
stage after passing through a series of moults. 
Longevity of the cockroach—Notes were made on the 
length of adult life (from the time of transforming into 
adults to the time of their death). All of these roaches 
were kept in glass jars with ample food. Thirty-nine 
males lived from 14 to 64 days, and 29 females lived from 
21 to 82 days, as tabulated below. 
Longevity Males Females| Longevity Males Females 
14 days 1 s 45 days she 3 
19 days 1 ae 48 days 2 2 
22 days 4 2 50 days 5 2 
25 days 1 se, 53 days 3 oa 
26 days 1 1 D0) days 2 
28 days ae 3 58 days se 1 
31 days 1 1 60 days 53 1 
32 days I 1 64 days =f 
33 days 1 as 82 days a 1 
38 days 6 4 —_> 
40 days 1 1 Total. 269 29 
42 days 7 3 
Thus we see that the average duration of life for the 
males was 40.2 days, and for the females 43.5 days. This 
difference is not great, but these few figures show at 
least that the females are inherently longer lived than 
the males, a condition that is often found in the insect 
world. 
