364 PARASITISM 



that the habit increases the capacity for destruction by the 

 hyperparasites concerned, since the primary parasites thus fed 

 upon always fail to develop. This peculiar method of feeding -^ 

 has been mainly recorded among Chalcids, with but few examples 

 among the Ichneumonoids, and it has also been noted in Vespoid 

 parasites of the family Bethylidse. 



In 1921 Trouvelot published observations, which were subse- 

 quently extended in a later paper (1924), upon a remarkable 

 development of the same type of behaviour in the Braconid 

 Habrobracon johannseni, which punctures the cocoons of its host, 

 the potato tuber moth. It appears that in piercing the cocoon, 

 in order to reach the moth larva within, the Braconid secretes at 

 the same time a viscid fluid which forms into a minute gelatinous 

 tube, thus establishing a connection between the body-fluid of 

 the larva and the exterior. After completion of the operation, 

 the parasite withdraws its ovipositor and applies its head to the 

 mouth of the tube and sucks the blood of the host through this 

 improvised funnel. In 1921 Lichtenstcin also recorded an 

 identical method of feeding in the Chalcid Hahrocytus cionicida 

 which oviposits in pupae of the weevil Cionus. Its ovipositor is 

 inserted through the cocoon of the host until it enters the pupa 

 within ; the organ is retained in this position for about thirty 

 minutes, until the secretion hardens around it, after which it is 

 withdrawn and feeding takes place. Faure (1924) has described 

 the same process in considerable detail with respect to two Chalcids 

 of the genera Pteromalus and Eurytoma, which parasitise Apanteles 

 glomeratus after the latter has formed its cocoon. He concludes 

 that the habit is probably frequent as a method of extracting 

 nutriment from hosts enclosed in cocoons, or in other receptacles, 

 which offer difficulties to feeding by the more direct method 

 already described. Other instances of this remarkable phase of 

 behaviour are alluded to by Faure which render it unnecessary 

 to make further mention here. 



Phoresy. According to Howard (1927) P. Lesne proposed the 

 word phoresie in 1896 with reference to cases where one animal 



^ Many recorded instances are enumerated by Wheeler, The Social Insects, 

 London, 1928, p. 52. 



