296 



SCIENCE- G OS SIP. 



Sibbald in 1684, reference is made to " Blatta, the 

 moth-fly," which, although the term is unfamiliar, 

 may possibly have been our common cockroach. 

 It is often difficult to determine to what insects 

 these early writers referred, more especially, per- 

 haps, in the group we are considering ; for, in 

 addition to the loose application of the word Blatta 

 before alluded to, our Cursoria have at various 

 times been included with hexapods now recognised 

 as belonging to quite different orders. We have, 

 however, no trouble in discovering, either from the 

 description or plates of the "Mill Beetle" in the 

 " List of Coleoptera" in the Companion to Buffon's 

 "Natural History," our oldfriendthe "black beetle," 

 with " his feelers like bristles, and two horns (i.e. 

 cerci) on the tail, and prickly legs." As neither 

 Johannes Jonstones (2"), Johannes Godartius (-'), 

 nor Oliver Goldsmith (--) makes any mention of 

 the cockroach, though writing discursively on such 

 kindred insects as the locust, grasshopper, mole- 

 cricket, etc., we may conclude that it had not 

 spread to any great extent in the country, espe- 

 cially as that great observer Gilbert White, writing 

 about 1787 — two hundred years or more after their 

 known existence in London — speaks of their ap- 

 pearance at Selborne, scarce fifty miles distant, as 

 " an unusual insect in one of my dark chimney 

 closets " (25). This would seem to show that the 

 invasion of the cockroach was carried out slowly 

 and unobtrusively, albeit with a determination and 

 thoroughness worthy so great and ancient a race. 



Blatta orientalis is not the only member of its 

 family in whose breast has been planted the love 

 of adventure and conquest. Periplaneta amerieana 

 Linn. (fig. 1) long ago anticipated our American 

 cousins' newly evinced desire for expanse of empire. 

 Many years have now elapsed since, chafing at the 

 narrow confines of the New World, it crossed the 

 seas and established itself in Europe, Asia, and 

 Australasia. This is the species, too, which is 

 often so prevalent on shipboard, many vessels being 

 completely overrun with it. It is a larger insect 

 and slightly lighter in colour than our common cock- 

 roach, a detailed description of which forms the 

 concluding portion of the piresent article. It 

 further differs from B. orientalis in having the 

 tegmina or wing-cases developed in both sexes, 

 longer than the body, and rounded at the apex. 

 The disc of the thorax is pale yellow, but the fact 

 of its having an irregular dark central patch gives 

 to the shield the appearance of bearing an ill- 

 defined yellow ring, which, though always present, 

 varies considerably in size and distinctness in 

 individual insects. The length of this cockroach 

 is aljout an inch and a quarter (28-33 mm.). The 



(20) " A Hist, of the Wonderful things of Nature," Loudon, 

 1657. 



(21) " Of Insects, done into English and Methodized," York 

 1682. 



(22) "A History of the World and Animated Nature" 

 (4 vols.), London, 1774; Liverpool, 1811. 



. (23) Selborne, " (Jhs. on Insects." 



species orientalis is by many entomologists in- 

 cluded in this genus, but our distinguished British 

 Orthopterist, Mr. Malcolm Burr, to whose (**) and 

 Professor Miall's exhaustive monographs (-') I am 

 very considerably indebted in the present paper, 

 has revived the term Blatta ; and if the law of 

 priority holds good this generic title should be 

 retained, as it was first used by Linnaeus to de- 

 scribe the type orientalis in 1745. 



P. amerioa/na is a native of Tropical America, 

 but has been recorded from London and several 

 other localities in England, in some of which it 

 appears to be permanently established. 



Peri/planneta australasiae Fabr. (fig. 2) is not 

 unlike the latter insect, but is smaller and easily 

 distinguished by the distinctness of the thoracic 

 markings, the yellow " ring," although varying 

 very greatly in breadth in different insects, having 

 the edges always clearly defined. The tegmina, 

 in addition to being obviously shorter than in the 

 preceding species, bear a well-defined longitudinal 

 yellow streak on their anterior margins, running 

 about one-third of their length. The size of this 

 insect is about an inch and an eighth (25 mm.). 



Originally a native of. Australia, this cockroach 

 has now spread with commerce to divers parts of 

 the globe. Mr. Burr mentions that it was first 

 captured at Belfast, but it has since been taken in 

 hot-houses at Kew (Mr. Lucas) and other parts of 

 the kingdom. My own specimens are from Waver- 

 tree (Liverpool), and were kindly obtained for me 

 by my friend Mr. Oulton Harrison, who states that 

 in the green-houses where they occur they are 

 believed to occasion damage by eating the aerial 

 roots of orchids. 



Compatibly with the national character, Phyllo- 

 dromia germanica Linn. (figs. 5 and 6) has also 

 founded colonies in many climes — regions as widel.y 

 separated as France and Australia, Mexico and 

 Japan, North America and Ceylon. This is the 

 " Croton-bug " of the United States, into which it 

 was introduced from Europe. It is especially 

 prevalent about water-pipes, etc., and obtained its 

 popular name on account of its being first 

 observed at the time that water from the river 

 Croton was brought into the city of New York 

 (" Stand. Diet."). It has now, however, spread 

 pretty generally throughout the country. Of 

 introduced species this insect more closely re- 

 sembles our native ones than do any of the others, 

 but is readil}^ separable from them by its larger 

 size (11-13 mm.), by the two well-marked dark 

 longitudinal bands on the pronotum, " by the ab- 

 sence of the apical area of the wings, and by the 

 venation of the elytra " (Burr). The general colour 

 is reddish testaceous, the males being lighter, and 

 in form narrower than the females, the wings being 



(24) "British Orthoptera," by Malcolm Burr, F.Z.S., etc., 

 Huddersfield, 1897. 



(25) " The Cockroach," by L. 0. Miall, F.E.S., and A. Denuy. 

 F.L.S. Leeds, 1886. 



