COCKROACHES. 5 
where the large American roach occurs they sometimes swarm in this 
way at night in such numbers that upon entering a small room in 
which they are congregated one will be repeatedly struck and scratched 
on the face and hands by the insects in their frantic flight to gain 
concealment. 
The black roach 1s less active and wary than the others, and particu- 
larly the German roach, which is especially agile and shy. 
The domestic roaches are practically omnivorous, feeding on almost 
any dead animal matter, cereal products, and food materials of all 
sorts. They are also said to eat their own cast skins and egg cases, and 
it is supposed that they will attack other species of roaches, or are, per- 
haps, occasionally cannibalistic. They will also eat or gnaw woolens, 
leather (as of shoes or furniture), and frequently are the cause of exten- 
sive damage to the cloth and leather bindings of books in libraries 
and publishing houses. The sizing or paste used on the cloth covers 
and in the binding of books is very attractive to them. The surface of 
the covers of cloth-bound books is often much scraped and disfigured, 
particularly by the German cockroach,! and the gold lettering is 
sometimes eaten off to get at the albumen paste. On shipboard the 
damage is often very extensive on account of the vast numbers of 
cockroaches which. frequently occur there, and there are reliable . 
accounts of entire supplies of ship biscuits having been eaten or 
ruined by roaches. 
The damage they do is not only in the products actually consumed, 
but in the soiling and rendering nauseous of everything with which 
they come in contact. They leave, wherever they occur in any num- 
bers, a fetid, nauseous odor, well known as the “‘roachy”’ odor, which 
is persistent and can not be removed from shelves and dishes without 
washing with soap and boiling water. Food supplies so tainted are 
beyond redemption. This odor comes partly from the excrement, but 
chiefly from a dark-colored fluid exuded from the mouth of the insect, 
with which it stains its runways, and also in part, doubtless, from the 
scent glands, which occur on the bodies of both sexes between certain 
segments of the abdomen, and which secrete an oily liquid possessing 
a very characteristic and disagreeable odor. It frequently happens 
that shelves on which dishes are placed become impregnated with this 
roachy odor, and this is imparted to and retained by dishes to such an 
extent that everything served in them, particularly liquids, as coffee or 
tea, will be noticed to have a peculiar, disgusting, foreign taste and 
odor, the source of which may be a puzzle, and will naturally be sup- 
posed to come from the food rather than from the dish. 
The roaches are normally scavengers in habit and may at times be 
of actual service in this direction by eating up and removing any dead 
animal material. 
1 Blattella germanica L. 
