SOME HYMEXOPTEROUS PARASITES OF LIGNICOLOUS 



ITOXIDII)^. 1 



By Charles T. Brues. 



Received Jan. 18, 1922. Presented Jan. 11, 1922. 



TiiE interesting material which led to the preparation of the present 

 paper was obtained by Professor W. M. Wheeler during the summer of 

 1920, when he visited the Tropical Research Station maintained by 

 the New York Zoological Society under the direction of Mr. William 

 Beebe at Kartabo, British Guiana. While exploring the forest in the 

 vicinity of the laboratory he found upon the surface of some freshly cut 

 stumps of trees, numbers of a minute species of gall-midge, the females 

 of which were ovipositing in the lumen of exposed vessels of the wood. 

 The larvse of these midges undoubtedly feed within the vessels and 

 their presence attracts swarms of very small Hymenopterous parasites 

 of the family Platygastridse, which are seen scattered over the moist, 

 freshly cut surface depositing their eggs within the bodies of the midge 

 lar^•ui upon which they are parasitic. Professor Wheeler secured speci- 

 mens of the midges and a large series of the parasites which he very 

 kindly turned over to me, thinking that they would prove of interest 

 on account of the extremely long abdomen possessed by some of the 

 parasites, whereby they are enabled to deposit their eggs in the host 

 larvae within the vessels, well below the surface of the wood. The 

 midges are similarly modified for this purpose as the apical abdominal 

 segments are very slender and form an extrusible tubular ovipositor 

 which can also be inserted into the interstices of the woody tissue. 

 Dr. E. P. Felt has been so good as to examine the midges and informs 

 me that they are probably referable to the genus Janetiella Kieffer, 

 although a knowledge of the male might show them to represent a new 

 genus. Felt ('18) lists a number of North American .species of Jane- 

 tiella that produce galls on very diverse plants (Pinaceae, Vitacese and 

 Myricacese) and one that occurs under decaying bark of chestnut, but 

 cites no zoophagous forms. Janetiella occurs in Europe and both 

 North and South America. 



The parasites proved to be of much greater interest than had been 



1 Contribution from the Entomological Laboratory of the Bussey Institu- 

 tion, Harvard University, No. 196. 



