A. D. Imms 215 



Pimpla, depends upon the time of oviposition by the latter. The earliest 

 hatched larvae meet with larval weevils only, but the later examples 

 will, more often than not, find the host in the pupal condition. Which- 

 ever occurs the life of the parasite is the same. Its young larva is usually 

 to be found on the dorsal side of the host larva, with the mouth-parts 

 immersed within the tissues of the latter. The position occupied by the 

 parasite is not constant since the latter was found attached to its host 

 in the following situations: to the fourth tergum; between the eleventh 

 and twelfth terga ; to the eighth tergum ; between the third and fourth 

 terga ; to the second tergum ; to the sixth tergum and, in one instance, 

 between the twelfth and thirteenth sterna. 



If it be the pupa that is attacked, the parasite was invariably ob- 

 served to select the anal extremity of the latter. Half-devoured pupae 

 were often met with, the abdomen being largely shrunken away, though 

 the remaining portion of the host appeared to be quite fresh, and ex- 

 hibited no signs of discoloration or putrefaction. Under these circum- 

 stances, it appears not unlikely that the parasitic larva may inject some 

 kind of secretion into the tissues of its host, serving as an antiseptic 

 arresting decomposition. 



Only a single parasite was found in relation to each individual host, 

 and a good deal of overlapping of the development stages was found to 

 occur — a feature which is far from rare among hymenopterous parasites. 

 Thus, on May 25th, I found Pimpla larvae 2 mm. long, half and fully 

 grown larvae, larvae commencing to spin their cocoons, and fully formed 

 pupae from among less than fifty examples of the Anthonomus. 



When fully fed, the larva spinsa slight silken cocoon, which is ovoid 

 in shape, measuring on an average 6 mm. long and 2 mm. in diameter 

 (Text-fig. 5). The cocoon can be readily detected within the cavity of 

 the affected apple bud; the silk of which it is composed is white, or, in 

 some instances, the outer fibres thereof are pale brown in colour. When 

 examined under a low power objective, the fibres can be readily observed 

 to be arranged for the most part in a circular manner around girth of 

 the cocoon. The whole structure, and the interstices between the threads, 

 is varnished over with a very thin and transparent layer of glutinous 

 secretion. 



Under laboratory conditions, the first example issued on June 17th, 

 1916, and was a male, the actual time being twenty-three days from the 

 date of commencement of spinning the cocoon. From the above date 

 onwards, until July 5th, a large number of the parasites emerged, the 

 first female appearing on June 21st. 



