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♦ KNOWLEDGE ♦ 



[August 1, 1889. 



sam<; parts of the globe. Such of these as survive the voyage 

 stand a chance, after unshipinent, of becoming naturalised, 

 if only they can speedily find suitable food and a locxlity 

 which yields a congenial temperature. Amongst such 

 established importations, of which we may now count some 

 dozens of examples, the common cockroach stands pre- 

 eminent as regards both size and number.^, and is probably 

 as cordially hated as any of them except the bed-bug. When 

 the first Asiatic cockroach set foot in Britain, it is impos- 

 sible to Sixy with certainty, but it was probably not more 

 than about four centuries ago. By the end of the .sixteenth 

 century, they had been introduced into the two chief maritime 

 countries of Europe — England and Holland ; but we do not 

 get any specific notice of them in zoological literature till 

 near the middle of the seventeenth century, when we read of 

 them as found in flour mills, wine cellars, Arc, in England. 

 At this early date, it was, of course, only the seaport towns, 

 and principally London, that vrere frequented by the insect, 

 and it took a long time to spread to inland and country 

 districts — indeed, in all probability, the conquest of England 

 by the cockroach is hardly yet complete. Gilbert White, 

 writing towards the close of the last century, speaks of the 

 cockroach as an unusual insect in the village of Selborne, 

 sajdng that he had never seen it in his house before, and no 

 doubt there are even now remote country places whither it 

 it has not yet penetrated. 



Cockroaches are strictly nocturnal in habits, seeking in 

 the daytime the utmost concealment. Hence it happens 

 that they often exist in our houses in multitudes that are 

 perfectly unsuspected until one surprises them in their mid- 

 night revels. You visit the kitchen after the lights are 

 out ; and as you approach a faint rustling, like the rattling 

 of distant rain, or the pattering of tiny feet, catches your 

 ear. You throw a light on the scene, and on the floor stands 

 revealed a sort of Pandemoniiim, crowded with dark forms 

 hurrying hither and thither, hastening to get into obscure 

 corners away from the glare of the hateful and unexpected 

 light. But when you go in again by daylight they have all 

 disappeared, and no trace of them can be seen. They have 

 packed and squeezed themselves away into niches, cracks, 

 and crevices, under sacks or matting, behind jars or pans, or 

 even under boards, bricks, or stones — anywhere to be out of 

 the light. The flatness of their bodies gives them unusual 

 facilities for thus bestowing themselves. 



They have a double reason for frequenting the kitchen 

 premises. First, a tolerably high temperature is essential to 

 their well-being, as might be expected of importations from 

 the tropics ; they cannot stand cold, and much less than the 

 frosts and snows of winter is suflioient to kill them. There- 

 fore they have the good sense to take up their quarters in 

 that part of the house where artificial warmth is most con- 

 stantly kept up. Then, again, the kitchen regions are the 

 land of plent}', and contain things edible to a greater extent 

 than the rest of the house. Not that they are at all 

 fastidious as regards diet ; the most unpromising materials 

 yield them sustenance, and they will absolutely thrive on 

 what might have been supposed to be totally innutritions. 

 They .are truly omnivorous ; articles of human food, both 

 animal and vegetable, are much to their taste, but they do 

 not stop at these ; woollen clothes, newspapers, blacking, 

 ink, leather, and even emery paper will do equally well, and 

 they will even devour their own oast skins, and enjoy a 

 cannibal feast on the corpses of their relations. Professor 

 Moseley records how, during the circumnavigating voyage 

 of H.M.S. Challenger, a number of cockroaches, stowaways 

 on the voyage, established themselves in his cibin, and 

 devoured parts of his boots, " nibbling off all the margins of 

 leather projecting beyond the seams on the upper leathers." 

 The same naturalist gives an amusing account of the 



attempts he made to rid himself of one particularly un- 

 pleasant visitor (apparently a different species from /'. 

 orientalis, though of similar habits), which seems to have 

 manifested a considerable degree of intelligence. He .says : 

 " 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 antenna" 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, lie 

 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 un- 

 pleasant, 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 la.st T 

 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." 



On board ship cockroaches, of one kind or other, often do 

 much damage. Mr. R. H. Lewis speaks of two kinds of 

 them attacking a cargo of 300 cases of cheeses. Holes had 

 been left in the packages to prevent the cheeses from 

 " sweating," and the cockroaches thus found entrance and 

 damaged them considerably, devouring a great quantity and 

 befouling all. Their disgusting odour, arising from a fnotid 

 fluid poured out from the mouth, renders them far more 

 obnoxious than they would otherwise be, and often causes 

 food to be spoiled by their proximity. 



In the perfect condition the male and female cockroaches 

 differ considerably. The males are smaller and less robust 

 than the females ; they stand higher on their legs, i.e., do 

 not allow their abdomens to trail along the ground as their 

 partners do, and are fuinished with two pairs of wings, the 

 females being apterous, or nearly 

 so. The upper pair of wings, 

 called ely tra 01' te(/mina(6g. 2, a) 

 are rather stiff and horny, and 

 being dark coloured, do not 

 easily show the very peculiar 

 course of the so-called ner- 

 vures ; but the under pair, 

 called specifically vnngs (fig.2, b) 

 are membranous and trans- 

 parent, and the nervures can 

 be easily seen. In repose the 

 wings are folded in half length- 

 wise, the inner half being bent 

 under the outer, and then itself 

 folded like a fan, and they are 



then covered by the elytra much as in a beetle, though in 

 that case the folding would be transverse instead of longi- 

 tudinal, and the elytra would not, as they do here, overlap. 

 When closed the elytra cover the greater part of the back. 

 The females simply have a rudimentary pair of elytra 

 (see fig. 1) and no wings at all, and flight is impossible to 

 them. 



A cockroach issues from the egg, not, like many insects, 

 with a form totally unlike that of its parents, but shaped 

 very similarly to the adult, and differing from that chiefly 

 in its minute size, its pale colour, and the absence of wings. 

 The.se young cockroaches may often be seen in kitchen hearths 

 in great numbers — little pale whitey - brown creatures, 

 running about with extreme agility, and moving their legs 

 so quickly that they seem to skim along or glide over the 

 ground. As they grow, like other insects they cast their 



FiG.2. — A, Elytron ;b. Wing, 

 OF Male Cockroach. 



