HA RDWI CKE 'S SCIENCE-GOSSIP. 



59 



species of dianthus. It might be that somebody had 

 told him thus, and that he believed it. I did not. 

 Rhododendrons are said to be hybridised, but are 

 not commonly double-flowered, nor are hybrid 

 gladioli. Of pelargoniums, the one most commonly 

 seen with double flowers is P. zonale, which in that 

 condition does not show any signs of hybridism. So 

 that it seems as if a variety of considerations point to 

 the conclusion at which I have arrived, that double 

 flowers are the consequence of a course of self- 

 fertilisation under conditions favourable to the vital 

 energy of vegetative growth. 



John Gibbs. 



THE NATURAL HISTORY OF THE COCK- 

 ROACH {PERIPLANETA ORIENTALIS). 



By Professor L. C. Miall and Alfred 

 Denny. 



[The present is the first of a short series of sketches 

 which will deal with the natural history, structure, 

 and physiology of one of our commonest msects.] 



THE cockroach or black-beetle is, to our sorrow, 

 very widely distributed in England, as in other 

 commercial countries. It is not a native of Europe, 

 nor does any member of the genus, as now limited by 

 naturalists, belong strictly to the European fauna. 



The species of cockroach which the English 

 naturalist may expect to meet with are enumerated 

 and shortly characterised in the following table. 



Order Orthoptera. 



Section Ciirsoria (One family only). 



Family Blattina. Legs adapted for running only. 

 Abdomen usually flattened. Wing-cases usually 

 leathery, opaque, overlapping (if well developed) 

 when at rest. Head vertical, retractile beneath the 

 pronotum. Eyes large, ocelli rudimentary, antennae 

 long and slender. 



Group I. Both sexes wingless {Polyzosferia). 



Group 2. Males winged, females wingless [Peri- 

 sphceria, Heterogamia). 



Group 3. Both sexes with more or less developed 

 wings (about 10 genera). 



Genus Blatta. A pulvillus between the claws of the 

 feet. The seventh sternum of the abdomen entire ; 

 no externally visible sub-anal styles in the male. 



B. Lapponica. Smaller than the common cockroach. 

 The wing-cases and wings long in both sexes. 



This is the insect of which Linnreus tells, that in 

 company with Silpha Lapponica it has been known to 

 devour in one day the whole stock of dried but 

 unsalted fish of a Lapp village. Out of Lapland it 

 has no home among men, but frequents thickets over 

 a great part of Europe. 



B. ericetorimi. This, and some other species of 

 which we have no critical knowledge, have been 

 described as natives of England, They frequent the 



sea-shore, where the larvse may be taken under 

 stones, or marshes and woods not far from the coast, 

 B. Gcrmauica. The wing-cases and wings are well 

 developed in both sexes. Two longitudinal stripes 

 on the pronotum or first dorsal plate of the thorax 

 are the most certain mark of this species, which is 

 considerably smaller than our common cockroach. 

 There is little doubt that Germanica is a native, not 

 of Germany, as the name implies, but of Asia and 

 the extreme east of Europe. To the Swede Linnreus, 

 who named the species, it was truly the German 

 cockroach, but Germany is now known to have 

 received the unwelcome guest from Russia, where, 

 especially in Asiatic Russia, it occurs wild, feeding 

 upon the leaves of the birch. The Russians, it is 

 true, disclaim the credit of originating this pest, and 

 to many Russian peasants the insect is known as the 

 Prussian cockroach (Fischer de Waldheim), tradition 

 affirming that the Russian soldiers brought it back 

 in their knapsacks from the seven years' war. 



Genus Periplancta. Readily distinguished from 

 Blatta by the divided seventh abdominal sternum of 

 the female and the sub-anal styles of the male. 



P. orientalis. The wing-cases of the male reach 

 the 5 th abdominal segment, and the wings the 4th 

 abdominal ; in the female the wing-cases reach only 

 to a little beyond the middle of the last thoracic 

 segment, while there are no free wings. This species 

 is native to tropical Asia,* and long ago made its 

 way by the old trade-routes to the Mediterranean 

 countries. At the end of the sixteenth century it 

 appears to have got access to England and Holland, f 

 and has gradually spread thence to every part of the 

 world. 



P. Aitiericana. The wings and wing-cases of this 

 species, which is much larger than orientalis or 

 Ger?}ianica, extend to the end of the abdomen in both 

 sexes. It belongs to tropical America, but occurs 

 sporadically in all countries which trade with 

 America. 



An Australian species also [P. Australasia:) has 

 been observed beyond its native limits in Sweden 

 (De Borck, " Skandinaviens riitvingade insekters 

 Nat. Hist." I. i. 35) and in Florida (Scudder, " Proc. 

 Boston Soc. N. H.," vol. xix. p. 94). In Florida it 

 is said to be the torment of housekeepers. 



Panchlora Maderce is said by Stephens to be 



* Linnseus was certainly mistaken in his remark (Syst. Nat.) 

 that this species is native to America, and introduced to the 

 east — " Habitat in America: hospitatur in Oriente." 



•f- This is to be inferred from Moufet's " Insectorum Theatrum" 

 (1634), in which he speaks of the Blattae as occurring in wine- 

 cellars, flour-mills, &c., in England. It is hard to determine 

 in all cases of what insects he is speaking, since one of his rude 

 wood-cuts of a " Blatta" is plainly Blaps mortisaga ; another 

 is, however, recognisable as the female of P. orieyitalis, a third 

 more doubtfully, as the male of the same species. He tells 

 how Sir Francis Drake took the ship Philip (of Spain ?) laden 

 with spices, and found a great multitude oi winged Blattae on 

 board, " which were a little larger, softer and darker .than 

 ours." Perhaps these belonged to the American species, but 

 the description is obscure. Swamraerdam was also acquainted 

 with our cockroach as an inhabitant of Holland early in the 

 serenteenth century (Bibl. Nat. p. 92). 



