Predaceous Insects and their Prey. 365 



foes of the Ichncumonidx* The other insect prey is very 

 varied : a Bracon ?, a Tenthredinid, two flies, (a Syrphid 

 and an Empid), a Panorpa and a small moth. Further 

 material is greatly needed in order to test the provisional 

 conclusions here arrived at, and to afford grounds for 

 estimating the relative influence of the various species 

 of the genus. 



Basypogon {Selidopogon) diadcina, Nos. 11 — 55. — The 

 record in the case of this species is remarkably complete, 

 no less than 45 examples being tabulated. Of these all 

 except one, in which the nature of the prey is uncertain, 

 are available for an analysis which demonstrates at a 

 glance the relative preferences of this predaceous species. 



The Prey of Basypogon {SelidopogoTi) diadema. 



Hemiptera. 



Coreidm ........ 1 



Total . . 1 



coleoptera, 



HydrophilidiB ....... 1 



CofridiB ........ 1 



GlaphyridsR ....... 3 



GetoniidsQ (abandoned) 1 



Total . . . 6 



* That the Hymenoptera are the special victims of Dioctria was 

 well known to Kirby and Spence. Thus we read (Fifth edn. 1828, 

 vol. i, p. 274) : — " The Asili also, which are always upon the chase, 

 seize insects with their anterior legs and suck them with their haus- 

 tellum. The cognate genus Dioctria, particularly DJcelandica, prey 

 upon Hymenoptera, by some unknown means instantaneously killing 

 the insect they seize." 



This last observation is also of great interest. The collapse of the 

 Asilid's victim — often an active powerful insect — is so instantaneov;s 

 that there can be little doubt that a poison is injected. In the case 

 of Laphria gibbosa (No. 86) which was devouring the Buprestid 

 beetle Ancylocheir a Jiavomaculata (see p. 339) the proboscis was thrust 

 through the cephalo-thoracic articulation. Dr. Chapman has pointed 

 out to me that if the beetle had not been already killed or killed 

 the instant of insertion it could have crushed the Asilid's proboscis 

 with ease. When an Asilid is captured and held by the wings it 

 often extrudes as if in defence a frothy liquid from the end of its 

 proboscis ; and it is probable that this is the poison. It would be 

 interesting to experiment upon insects with it, introducing a minute 

 quantity by means of a finely drawn out glass tube. 



