234 



not quite developed ovaries. The females of both these lots kept in 

 the insectarium, reached sexual maturity in 5-6 days and proceeded 

 to oviposit, the eggs producing caterpillars in five days. These females 

 were periodically dissected, and it appeared that during the process 

 of oviposition the fat-body gradually diminished, and in some cases 

 completely disappeared before all the eggs were deposited. Both the 

 fed and unfed females showed the same further development of the 

 ovaries and oviposited, the only difference being that the fed insects 

 lived somewhat longer after the oviposition than the unfed. A rise 

 in the temperature from 26° to 35° therefore leads to a progressive 

 development of the fat-body and a more or less proportional develop- 

 ment of the ovaries. The difference does not, however, materially affect 

 the further maturing of the ovaries, the other conditions being equal. 



The dissected females of the third (19°) and fourth (16°) lots showed 

 a slightly developed fat-body and ovaries even less developed than in 

 the first two lots. Those which were kept in the insectarium did not 

 oviposit, either when fed or unfed. The temperature of 19° and 

 lower is evidently unsuitable for the development of the pupae, and 

 at 16° only five imagines hatched. 



In nature, females are often found with a strongly developed fat- 

 body and undeveloped ovaries, but these, contrary to the results 

 obtained in the laboratory, remain sterile. This was the case during 

 the summer of 1913, when all the females of the second generation 

 were sterile, although having well-marked fat-bodies. The reason 

 for this is uncertain, but it cannot be attributed to excessive heat over 

 36°, which according to experiments of V. P. Pospielov leads also 

 to sterility, as the weather during the summer was cool and rainy. 



Cold weather, bordering on the temperature at which the caterpillars 

 pass into a state of diapuse, interferes with the development of the 

 ovaries and leads to the fat being consumed for other processes ; 

 the females hatch out with undeveloped ovaries and not having a 

 supply of fat the eggs cannot mature and no feeding can restore the 

 sexual maturity to such females. In nature such specimens seldom 

 appear, as under such conditions the caterpillars pass into a state of 

 diapuse and do not pupate, awaiting more favourable conditions. 



During the discussion, V. Averin drew attention to the importance 

 of also taking into consideration the influence of moisture on the 

 development and fertility of P. sticticalis. He stated that his experi- 

 ments have shown that a great degree of moisture prevents the develop- 

 ment of the oviducts of that insect. Replying to A. Silantiev, who 

 suggested that possibly the fertihty of the females, which were fed, 

 was due to the presence of some micro-organisms, the author denied 

 the possibility of this, as the females from the 2nd and 3rd chambers also 

 oviposited, and preparations of the oviducts and of the fat-body of the 

 fertile females did not correspond with the description given by 

 Krassilstchick of infested tissues. 



KoROLKOv(D.M.). YcnoBifl nprnvitHeHifl Mtpi* 6opb6bi ctj caflOBbiMM 

 BpeAMTenflMM eii KpecTbAHCKHx-b xosfliiCTBax-b caAOBaro paiOHa 

 MoCKOBCKOti ryOepHJM. [The conditions for the application of 

 methods of controlling orchard pests in the peasant-husbandries 

 of the orchard region of the govt, of Moscow.] pp. 78-83. 

 Investigations as to how far various remedies against orchard 



