LARVA-PUPA. 7 



and moisture. I have observed, also, that they are 

 very often assorted according to age. It is sometime* 

 very curious in my nests to see them arranged in 

 ^r.inps according to size, so that they remind one of 

 a school divided into five or six classes. 



As regards the length of life of the larvae, Forel 

 supposed 1 that those of Tapinoma matured the 

 quickest, and were full-grown in about six or seven 

 weeks. Some of Myrmica ruginodis, however, ob- 

 served by me, turned into pupae in less than a month. 

 In other cases the period is much longer. In certain 

 species, Lasius flavus, for instance, some of the larva? 

 live through the winter. 



When full grown the larvae turn into pupae (PL V. 

 fig. 4), sometimes naked, sometimes covered with a 

 silken cocoon, constituting the so-called * ant-eggs.' 

 We do not yet understand why some larvae spin 

 cocoons, while others remain naked. As a general 

 rule, the species which have not a sting, are enveloped 

 in a cocoon, while those which have, are naked. 

 Latrielle was the first to observe that in one species 

 (F. fused) the larvae sometimes spin a cocoon, and 

 sometimes remain naked. The reason for this differ- 

 ence is still quite unknown. After remaining some 

 days in this state they emerge as perfect insects. 

 In many cases, however, they would perish in the 

 attempt, if they were not assisted ; and it is very pretty 

 to see the older ants helping them to extricate them- 



1 Let Hntmi* de la Sttiftf, p. 420. 



