October, '081 JOURNAL OP ECONOMIC ENTOMOLOGY 287 



of the reproduction experiments which were conducted in large tubes. The 

 first full-grown larvae were found on the 11th, but it is probable that these 

 were more advanced upon the 9th than those actually observed upon that day. 



"Young larvse were found in eggs which contained the beetle embryo suf- 

 ficiently developed to show traces of the legs and head. Many eggs containing 

 embryos further advanced were examined at the same time, and, though these 

 seemed to be dead as the result of oviposition by the parasite, no parasite 

 larvae could be found. The parasite will oviposit, or appear to oviposit, in 

 eggs containing beetle larvae fully formed, but it is doubtful if, under such 

 circumstances, reproduction ensues. 



"In laboratory reproduction it is better not to have the eggs too fi'esh, as 

 they are much more likely to wither, if kept dry, or mold if kept damp, than 

 eggs several days old. It was first supposed that perfectly fresh eggs would 

 be better. A lot of beetles was confined indoors with elm leaves, and the 

 newly deposited eggs used in reproduction experiments. All of these experi- 

 ments were failures. In the open, with eggs on living foliage, the results 

 would probably be different. 



"Pupae were first noted on the 15th. The distinctive coloration of the pai'a- 

 sitized eggs was also noted at this time, and it was found possible to separate 

 those containing parasites by their color alone. 



"These parasitized eggs are somewhat suggestive of those containing larvse " 

 nearly ready to emerge, but lack the characteristic greenish hue. They are 

 grayish in tint and have a dull, dead appearance. They are frequentlj^ some- 

 what withered, and in the case of those from the reproduction experiments 

 were frequently covered with a scanty growth of mold. 



"The first adults of the new generation emerged on June 21, and appeared 

 in considerable numbers on that date. This would indicate a life cycle of 20 

 days, as it appeared that oviposition began at once upon the receipt of the 

 parasites. 



"Later generations developed more quickly. From the jar started on June 

 11, reproduction was secured on June 29, 18 days later. From the fresh egg- 

 masses placed in the same jar on June 18, reproduction was secured 16 days 

 later, on July 4. From the first lot of fresh eggs placed in the third jar, to 

 which the parasites were transferred on June 23, abundant reproduction was 

 secured on July 8, after but 15 days had elapsed. From the fresh eggs added 

 to this jar on June 26, reproduction was secured on July 11, another fifteen- 

 day period. The last jar, to which the parasites were transferred on July 

 1, contained, on July 15, adults in very small numbers, of what must be their 

 progeny, indicating a life cycle of but 14 days. 



"This gradual reduction in the length of the life cycle as the season ad- 

 vanced is peculiar, and no explanation is offered. The average temperature 

 during the latter part of June and first of July was higher than during early 

 June, but there hardly seems to be enough difference to account for six days 

 shortening of the life cycle of an insect which develops as rapidly as Tetras- 

 tichus." 



The adult parasites secured by laboratory reproduction were liber- 

 ated in two localities near Boston, and parasitized eggs were sent to 

 Prof. J. B. Smith at New Brunswick, New Jersey, and to Prof. ]\I. V. 

 Slingerland at Ithaca. New York, and the remainder wei-e sent to 



