PAIRING OF INSECTS. 209 



those circumstances ; and in the case of sittin^^ upon 

 the ei»'Q;s, the only instances in which it occurs being 

 among- spiders, who have their nets ready spread 

 contii^uous to their nest, or carry it about with them, 

 assistance seems to be little necessary. In the case 

 o mest-building, on the other hand, where laborious 

 operations have to be performed, we might have ex- 

 pected that the male would lend his assistance, such 

 as in the structures of the mason-bee, or the car- 

 penter-wasps * ; but, so far as we are at present aware, 

 the female performs the whole of the labour. The 

 only circumstance we remember, which bears any 

 resemblance to such mutual aid, occurs among a 

 species of solitary bees (Halictus) which constructs 

 galleries in sand-banks, but which, according to 

 Walckenaer, work only during the night, while, 

 during the day, either the male or the female always 

 remains at the entrance, prepared to repel the in- 

 trusions of enemies f- It does not appear, however, 

 that the male renders any assistance in digging out 

 the gallery which he thus helps to defend. 



In the instance of carnivorous insects, so far from 

 rendering each other mutual assistance, it is no unu- 

 sual occurrence for the one sex to attack and devour 

 the other ; and the female, being always the larger 

 and more powerful, usually overcomes her partner. 

 We know too little of the manners of fish, to assert 

 that similar habits prevail amongst them; yet it 

 seems by no means improbable that a hungry pike 

 (Esox lucms) would make little ceremony of devour- 

 ing his mate ; for it devours its own species as readily 

 as any other]:, some of considerable size having been 

 found in the stomachs of those that have been caught. 

 We have ourselves frequently caught mackerel, and 



* See Insect Architecture, chapters ii. and iii. 



f See Insect Transformations, p. 53, 4. 



% Donovan, Brit. Fishes, 109. 



T 3 



