CHAP. III.] METAMORPHOSIS. 33 



with congenial conditions. Observations on abnormally extended 

 pupal periods have chiefly been made in the case of Lepidoptera 

 in which Order pupa; from one batch of eggs, in the case of some 

 species at any rate, are known to eclose moths, some in the first 

 year after pupation and some in the second and subsequent years 

 up to the seventh or later. Such an irregular eclosion will give the 

 species concerned a better chance of survival by spreading the 

 descendants of one generation over several seasons, some of which 

 are likely to be favourable as regards climatic conditions or scarcity 

 of parasites, and will also tend to secure cross-fertilization between 

 different stocks. 



Although, as already noted, insects are usually developed from 

 eggs deposited by the parent female, yet in most groups (e.g., 

 Coleoptera, Lepidoptera. Diptera, Rhynchota) we meet with cases 

 of viviparity, that is to say, the female extrudes, not passive eggs, 

 but active living larvae. In the Pupiparous Diptera, of which the 

 common Dog-fly is a familiar example, the larva is retained and 

 nourished within the body of the female until it is full-grown, when 

 it is deposited and pupates immediately afterwards. Instead, 

 therefore, of the nutriment requisite to the growth and reproduction 

 of the individual fly being absorbed by the larva directly, it is the 

 adult fly only which feeds actively. 



In the great majority of cases the eggs are simply laid by the 

 female which takes no further care of them, and as a rule she dies 

 shortly after having deposited them. Sometimes the dead body of 

 the mother remains by the eggs and forms the first meal eaten by 

 the newly-hatched larvae. Even in cases where special provision 

 is made for the young, as in the examples offered by the solitary 

 wasps which collect and lay up a store of spiders or caterpillars on 

 which or near which the eggs are laid, instinct rathei than intelli- 

 gent solicitude seems to be involved, for the cell is sealed and left 

 to its fate. In some cases, however, true instances of maternal 

 tude are known to occur and it is not uncommon, for example, 

 to find a mother-earwig watching (one might almost say brooding) 

 over her eggs; on one occasion at Yercaud, on turning over a log, 

 I found a pair of earwigs with a pile of eggs which, when they 

 were disturbed, the female carried away in her mouth into a safer 

 place, whilst the male sought safety in flight. In the Hills also old 

 rotten logs are commonh found to contain Passalid beetles which 

 occur in little colonies, larva.-, pupae and adults often being found 

 together, and it has been shown that the adult beetles masticate 

 the wood with their jaws to render it fit for the food of the larvae 

 which are unable to feed by themselves on the unchewed wood. 

 ("are for the young l>\ the mother-insect is also well known to occur 

 3 



