300 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
accidental importations. It would obviously be incorrect to 
regard such waifs and strays as an essential part of the New 
England fauna, and unnecessary and out of place to include them 
here except briefly. For this reason the Key to Species aims to 
cover only those which are known to exist here naturally or to 
have maintained themselves for longer or shorter periods of time. 
The number of generations of these insects per year appears to 
differ with the species. Of the wild, native Roaches there is but 
one brood ; of the German Roach or ' Croton-bug' there are several, 
according to latitude; and the Oriental Roach is believed to re- 
quire several years to reach maturity. The eggs are usually laid, 
several at a time, enclosed in a horny, bean-shaped capsule called 
an ootheca (o-o-the-ca) which is carried about for several days 
protruding from the body of the female, and is finally dropped 
apparently at random in the haunts of the adult. The capsule 
opens along one side (in some species the inner, in others the outer 
side) by a seam. The young are said to secrete a liquid which 
dissolves the cement and allows them to emerge by pressing apart 
the lips of the seam. Some species are reported to be viviparous. 
It is said that the female in certain instances aids the young 
to escape. 
The sexes may generally be distinguished without difficulty, 
though there is no visible ovipositor. The males are character- 
ized in most genera, in addition to the conspicuous cerci, by the 
presence of a pair of styles. 
These are placed at the sides of 
the hind margin of the last ven- 
tral segment of the abdomen. 
The females of some genera have 
the last ventral segment cleft by fig. 24.— Egg capsule of Penpianeta 
a median fissure, dividing it into «™^"~ «, side; 6 eud view. Natural 
' ° size indicated by outline figure. (After 
obliquely sloping right and left Mariatt.) 
valves. 
Roaches are nocturnal insects, remaining quiet by day in the 
sheltering darkness of their abode. At night they sally forth 
seeking food, and attack everything edible, especially such articles 
as contain starch. Wall-paper, clothing, book-bindings, etc., are 
subject to their depredations as well as ordinary food stuffs, and 
the aggregate damage is very heavy, particularly in warm 
