THE COCKROACHES. 171 



crawled^ — all tend to justify the disfavour in which it 

 is held in well-regulated households. 



There is_, however, an interesting point in the 

 history of this insect and its allies, which must render 

 them worthy of the attention of the entomologist. 

 The eggs, instead of being emitted separately, as in 

 most other insects, are enclosed, to the number of 

 sixteen in the common Cockroach, in a peculiar horny 

 case, resembling a small bean, each egg being sepa- 

 rated from its fellows by small partitions. The depo- 

 sition of the egg-case is rather a difficult matter, as 

 might be expected from its size compared with that 

 of the insect ; it is said to be a week before the com- 

 mon species gets rid of it, whilst a smaller species, 

 the B. germanica, takes a fortnight in this operation. 

 Along one side of the case is a slit, furnished with a 

 pair of toothed plates which fit closely together, and 

 further secured by a coating of a peculiar kind of 

 cement. When the larvae are hatched they emit a 

 fluid from their mouths by which the cement is 

 softened, and they are then able to push their way 

 through the slit, and make their escape into the world. 

 They are very like their parents, but of a lighter co- 

 lour, and destitute of the wings and wing-cases, which 

 afterwards usually make their appearance in the males ; 

 these organs in the other sex are often rudimentary. 



The characters of the tribe Blattina, to which our 

 common Cockroach belongs, may be briefly stated as 

 follows : — The head is deflexed, more or less concealed 

 beneath the front of the prothorax, and furnished 

 with a pair of long, slender, tapering antennae. The 

 legs are all formed for running, and the tarsi are 

 composed of five joints. The wings, when present, 

 fold up in the usual manner of the Orthoptera, but 



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