458 JOURNAL OP ECONOMIC ENTOMOLOGY [Vol. 2 



of keeping with the ordinary, as to demand additional substantiation. 

 Careful examination of the contents of one of these parasite cocoons 

 discovered nothing (the other was unfortunately lost) but when the 

 remains of the primary host were examined a quantity of second stage 

 Tachinid moult skins, and one dead and dried Taehinid maggot were 

 found. It seemed to prove conclusively that the maggots, threatened 

 with starvation through the more rapid development of their common 

 rival, had migrated into its body, and there continued their develop- 

 ment exactly as they would have done had they remained in un- 

 disputed possession of their original host. Additional color is given 

 to this conclusion by another instance involving the parasites of an 

 entirely different host, in which the young larva of one is known, 

 beyond peradventure of doubt, to have entered in a similar manner 

 the body of a rival. 



The Secondary Parasites 



Nothing approaching the tremendous percentage of hyperpara- 

 sitism recorded by Dr. Smith was encountered in the course of this 

 study. Dibrachys, of which he reared scores of thousands, is a very 

 common hyperparasite throughout southern New England, but was 

 very rare in this connection. One mass of Spilocryptus cocoons a 

 year or more old was found to have been infested, and a few dead 

 pupffi and adults found. A very few were also reared from a few" 

 masses of the Spilocryptus cocoons which had been torn from their 

 original position in the cocoons of their hosts, and placed together in 

 a small cage. These immediately oviposited in the still dormant 

 larvae of the primary parasite, and a very much larger number of the 

 second generation were reared. 



Even when Spilocryptus was collected in mid-winter and exposed 

 to continuous high temperature until spring it did not complete its 

 transformations until after the press of regular spring work had made 

 further observations impracticable, and the date of its usual emer- 

 gence in the open is not known. It is very likely not until well into 

 June in this latitude, and Dibrachys which only requires one month 

 of average late spring temperature in which to complete its life cycle 

 has ample opportunity to complete one generation and probably two 

 before its host resumes activity. Unlike that species, it responds 

 almost immediately to "forcing" during the winter, so that no time 

 is wasted in making a start. It is likely, too, that only in somewhat 

 exceptional instances is it able to reach the well protected cocoons of 

 the Spilocryptus, since it has not been known to gnaw its way through 



