But, like other insects, cockroaches change their skin from time to time, and they lose little time before beginning this ecdysis, for they first cast their cuticle immediately after escaping from the egg-capsule. The second ecdysis is four weeks later, and the third at the end of the first year, and after this time they moult annually. At the seventh moult, when the animal is now four years old, it assumes the form of the perfect insect, and is capable of reproduction. The later moults fall in the summer time, and so does fertilisation and oviposition. Male cockroaches may be distinguished from the females by their well-developed wings and wing-covers. They stand higher on their legs than do the females, whose abdomens often trail upon the ground.
In spite of the noxious secretion of their abdominal glands there are creatures who habitually feed on cockroaches—hedgehogs, for instance, are frequently imported into our houses to check these pests. Rats, cats, polecats, frogs, and wasps have been known to eat them, and some few of the digging-wasps lay them down in their larders for the use of their progeny. Some birds will also tackle them. But even the most devoted friend of cockroaches can find little to say in their favour, except that they are currently reported to form the basis of the flavouring of a very popular sauce; but even wild cockroaches will not drag from me what the name of that particular sauce is.
CHAPTER II
COCKROACHES (Periplaneta)
Part II
In Russia the small Asiatic cockroach (P. orientalis) has everywhere driven before it its greater congener (P. germanica).
(Darwin, Origin of Species.)
Cockroaches do a very considerable amount of damage by consuming food-supplies. But they do not stop at food-supplies: woollen clothing, newspapers—not a really great loss—blacking, ink, leather, and even emery-paper, are all to their taste, and, being of an economical frame of mind, they devour their own cast skins and the dead bodies of their relatives. The late Professor Moseley recorded how on one occasion, when on the circumnavigating tour of H.M.S. Challenger, a number of cockroaches took up their abode in his cabin and devoured parts of his boots, ‘nibbling off all the margins of leather projecting beyond the seams on the upper leathers.’ He further records:—
One huge winged cockroach baffled me in my attempts to get rid of him for a long time. I could not discover his retreat. At night he came out and rested on my book-shelf at the foot of my bed, swaying his antennae to and fro, and watching me closely. If I reached out my hand from bed to get a stick, or raised my book to throw it at him, he dropped at once on the deck, and was forthwith out of harm’s way. He bothered me much, because, when my light was out, he had a familiar habit of coming to sip the moisture from my face and lips, which was decidedly unpleasant, and awoke me often from a doze. I believe it was with this object that he watched me before I went to sleep. I often had a shot at him with a book or other missile as he sat on the book-shelf, but he always dodged and escaped. His quickness and agility astonished me. At last I triumphed by adopting the advice of Captain Maclear and shooting him with a pellet of paper from my air-gun, a mode of attack for which he was evidently unprepared.
It is on record that cargoes of cheeses have been destroyed by cockroaches on ships. Not only did they devour great quantities of each cheese, but they defiled every one of them with their very tenacious fluid which has, as we have noted above, a most disgusting smell. This the cockroaches poured out from their stink-glands, making the cheeses of no commercial value.
