250 Apple and Pear SttcJcer 



is provided with two bristles. The larva is moving its antennae and 

 is possibly attracted to the bud by a kind of chemotropism ; otherwise 

 it is impossible to say why the larva should crawl up towards the bud, 

 which at this time is also sprouting. It sometimes happens that the 

 bud, on that twig, is not yet opened. In that case the larva is at a 

 standstill. It can live without food for two or three days, at the end 

 of which period it succumbs to death. But on the whole, the time 

 for the larva to hatch and the bud to blossom is so finely adjusted, 

 that the former has not to wait for the latter. 



II. Summary of the Life-History. 



There are in all five instars, the last of which is here called the 

 "Nymph," from which the adult insect emerges. Larvae were bred 

 artificially in the experimental house. The method of breeding them 

 was as follows : tender short apple twigs were cut and embedded in 



Fig. 4. Fig. 5. 



Fig. G. Fig. 7. 



wet silver sand in a museum jar, the top of which was covered with 

 a thin piece of muslin. The wet sand enabled the twigs implanted in 

 it to keep fresh for two or three days, at the end of which time they were 

 replaced by fresh twigs. The larvae were carefully picked from the 

 old twigs and placed gently on new ones. Thus it was possible to 

 study them very closely. The temperature of our room was equable 

 and was somewhat higher than that outside. Small apple trees were 

 used for checking the period of each stage, and it seems that this arti- 

 ficial method has no appreciable effect on the life-history of these 

 insects. 



