242 INSECT TRANSFORMATION 



The care of the worker-ants for the young does not terminate 

 with the final larval stage. Workers often excavate hollow 

 chambers in which the full-fed larvae can conveniently spin 

 their cocoons and pupate. The pupae swathed in their cocoons 

 (the so-called " ants' eggs ") are protected and carried about 

 if necessary by the workers, which afterwards assist the newly- 

 developed adults to emerge from the pupal cuticle and cocoon. 

 Then the prolonged tending of the preparatory instars of the 

 life-history is succeeded by comradeship in the activities of 

 the community among the older and younger adult sister- 

 workers. It may be mentioned that in many ant societies 

 there are several distinct castes of workers differing often in 

 their size, form and functions, as well as aberrant females 

 intermediate to some degree between workers and queens. 

 It must be regarded as doubtful whether, as in the case of the 

 hive-bees, these differences are determined by differences of 

 the food supplied during growth in the larval period. 



Ant grubs are thus among the most helpless and quiescent 

 of insect larvae, fed, tended and carried about by their adult 

 sisters. But in a few cases they help in the work of the nest, 

 albeit still in a manner largely passive. Certain genera of 

 tropical African and Eastern ants Oecophylla and Polyrhachis, 

 and Brazilian species of Camponotus make elaborately-formed 

 nests by fastening the edges of leaves together with silken 

 threads. The adult ants have no silk-producing organs, so 

 they induce the larvae to spin the required material ; while a 

 row of workers hold the edges of the leaves together with their 

 mandibles, other workers bring small larvae which play out 

 silken threads from their mouths as they are moved by their 

 carriers in the appropriate direction, the head-end of each 

 grub pointing forwards and upwards (Fig. 118). As a recent 

 observer 1 has described the process : " There could be no doubt 

 that the ants were actually using their larvae both as spools 

 and shuttles. As several workers toiled close together, they 

 were able to cross and recross the threads and thus produce 

 a rather tenacious tissue ". In the case of some of the species 

 that use their larvae as spinning machines in this remark- 

 able manner, the silk that would normally serve for the 



1 F. Doflein : " Beobachtungen an den Weberameisen ". Biol. Centralbl 

 XXV. 1905. 



