24 HYMENOPTERA CHAP. 



of great interest and variety. Fabre observed H. lineolatus and 

 H. sexcinctus l under circumstances that enabled him to give them 

 continuous attention, whenever requisite, throughout a whole year. 

 These bees are to a certain extent social ; they are gregarious ; each 

 bee works for its own progeny, but there is collaboration between 

 members of a colony, inasmuch as a piece of general work is 

 undertaken from which more families than one derive benefit. 

 This common work is a gallery, that, ramifying in the earth, 

 gives access to various groups of cells, each group the production 

 of a single Halictus ; in this way one entrance and one corridor 

 serve for several distinct dwellings. The work of excavation is 

 carried on at night. The cells are oval, and are covered on the 

 interior with a delicate waterproof varnish ; Fabre considers this 

 to be a product of the salivary glands, like the membrane we 

 noticed when speaking of Colletes. In the south of France both 

 sexes of these species are produced from the nests in September, 

 and then the males are much more numerous than the females ; 

 when the cold weather sets in the males die, but the females 

 continue to live on in the cells underground. In the following 

 spring the females come out and recommence working at the 

 burrows, and also provision the cells for the young ; the new 

 generation, consisting entirely of females, appears in July, and 

 from these there proceeds a parthenogenetic generation, which 

 assumes the perfect form in September, and consists, as we have 

 above remarked, in greater part of males. Perez, 2 however, 

 considers that Fabre's observations as to the parthenogenetic 

 generation were incomplete, and that males might have been 

 found a little earlier, and he consequently rejects altogether 

 the occurrence of parthenogenesis in Halictus. Nicolas con- 

 firms Fabre's observations, so far as the interesting point of the 

 work done for common benefit is concerned ; and adds that the 

 common corridor being too narrow to permit of two bees passing, 

 there is a dilatation or vestibule near the entrance that facilitates 

 passage, and also that a sentinel is stationed at this point. 



Smith's observations on Halictus morio in England lead one 

 to infer that there is but one generation, the appearance of which 

 extends over a very long period. He says, " Early in April the 

 females appeared, and continued in numbers up to the end of 



1 C.R. Ac. Paris, Ixxxix. 1879, p. 1079, and Ann. Sci. Nat. (6), ix. 1879, No. 4. 

 2 Act. Sue. Bordeaux, xlviii. 1895, p. 145. 



