231 [15] 



Note upon a Tachinid Parasite (Bucentes geniculatus, D. G.) 

 of Tipula sp. By John Rennie, D.Sc. 



(Read 23rd October 1911. Received 23rd October 1911.) 



In a collection of Tipula larvae undergoing examination for Protozoan 

 parasites a dipterous larva was found in the body cavity of a small number 

 of specimens. It was thought worth while to examine the remaining 

 specimens in hand for external signs which might serve to distinguish 

 infected from uninfected individuals. In a certain number of cases it was 

 noted that a yellowish patch was visible beneath the skin, more or less 

 sharply defined, and this was presumed to be the maggot within. Those 

 suspected were sacrificed, and the majority were found to be infected. In the 

 remaining cases the fat body had served to mislead. 



At this stage, which was in the month of February of the present year, 

 an attempt was made to keep the extracted maggots alive upon Tipula 

 flesh in salt solution, but this effort was not successful. 



With a view to ascertaining whether the parasite occurred widely, Tipula 

 larvae were obtained from two other sources, and in each case the parasite 

 was found in small numbers. The three localities from which infected 

 larvae were obtained were Old Meldrum and Clova in Aberdeenshire, and 

 Cornhill in Banffshire. From this it may be presumed that the parasite 

 is generally distributed in Tipula, in the north-eastern counties at all 

 events. From the known habits of the group (Tachinidae) to which the 

 parasite belongs, it is possible that other insect hosts exist. 



The Tipula larvae were now kept in soil in protected flower-pots, upon 

 which loose, fresh turf was periodically placed and in which oats were also 

 sown. This in due course germinated. From time to time the earth in 

 the pots was turned out and the larvae examined. Most continued in a 

 healthy condition — firm skinned and curling readily when handled. Some 

 were found in the act of moulting. On 22nd April out of over fifty larvae, 

 one dead and four very inert specimens were found. These living ones 

 appeared certainly infected ; one was sacrificed and from it a maggot 

 obtained. This was preserved alive in a petri dish upon the host tissue. 

 No parasite was found within the dead grub nor within another live 

 suspected one. The remaining suspected larvae, which were much smaller 

 than the others (about half an inch long), together with some other small 

 examples selected from the general collection, were now placed in soil in 

 a small glass observational jar 3J x 3 x J ins. in size, and protected by a 



