30 BRITISH ANTS. 



mediately after fertilization, whereas with others oviposition does 

 not take place until the year after the marriage-flight. The time 

 required for the eggs to mature varies very much both in different 

 species, and also under different conditions. It may only occupy 

 a few days, or it may require six weeks ; and unfertilized eggs take 

 much longer to hatch than fertile ones. A large proportion of the 

 eggs laid are eaten by the ants themselves, chiefly by the workers, 

 though also by the queens, both in new and in long-established 

 colonies. 



A young queen eats some of her own eggs, and also feeds her 

 first brood with them. 



A large number of the eggs laid by workers in queenless nests are 

 always devoured, and a worker will eat her own egg as soon as she 

 has laid it. 



Parthenogenesis. It was supposed that Dzierzon's theory for 

 the honey-bee, that unfertilized eggs only develop into males, 

 applied to ants also, but although Lord Avebury, Janet, Forel, 

 Miss Fielde and others have shown that this is frequently the case, 

 more recently Tanner, Reichenbach, Mrs. Comstock, Crawley, and 

 myself have proved that unfertilized eggs laid by workers can 

 develop into workers. 



Indeed, under certain circumstances such as the adoption of a 

 Donisthorpea umbrata, or D. mixta female into a nest of D. nigra or 

 D. aliena workers only seem to be developed from worker eggs. 



Crawley and I have also observed eggs laid by virgin females, 

 but on these occasions, when the eggs have developed, only males 

 were produced. 



The particulars of these different experiments when they con- 

 cern ants that occur in Britain will be found under the species in 

 question. 



Larvae. The larvae of ants belong to the vermiform type, being 

 without legs, or any trace of eyes. They are helpless white or 

 yellowish grubs, entirely dependent on the queens and workers, 

 and are usually pear-shaped, or sack-like, being broadest pos- 

 teriorly, but in a few cases they are cylindrical, or barrel-shaped, 

 i.e. broadest in the middle. 



The head is small, but distinct ; the neck is narrow and often 

 bent downwards over the ventral surface, considerably more so in 

 some species than in others. 



The body, exclusive of the head, usually consists of thirteen 

 segments, three belonging to the thorax and ten to the abdomen ; 

 the segmentation being well marked in some species, but consider- 

 ably less so in others, especially towards the posterior end. 



Ten pairs of tracheal openings are present, a pair each to the 

 meso- and meta-thorax, and the remaining pairs to the eight 

 anterior abdominal segments. 



The mouth parts are not as a rule strongly developed ; they 



