220 INSECT ENEMY OF GLOSSINA IN DAHOMEY. 



which still buzzed round the donkey, and placed it in a long glass tube, into 

 which I also introduced a living Glossiyia. After flying for some minutes in 

 a dazed manner along the sides of the tube, the Bemhejc perceived its prey, 

 pounced upon it and pierced it with a single thrust of its sting. No sooner 

 had I detected the movement of the abdomen than the fly appeared inert and 

 with folded wdngs, lying longitudinally beneath the body of the wasp, which 

 carried it firmly held between its posterior and middle legs. I repeated the 

 experiment upon another Bemhex, with the same result ; in an instant the 

 fly was paralysed by the sting, and placed in the carrying position. But 

 after having flown about for some minutes in their glass prison, the wasps 

 abandoned their prey in order to find a means of escape. The stung flies 

 were absolutely incapable of any movement. 



" The arrival of the Bembex around the donkey took place almost 

 immediately the latter was introduced into the longipalpis zone. On taking 

 the animal to various points of the area frequented by this Glossina, the same 

 Bembex appeared. I then led it some distance away to the river bank, in the 

 palpalis zone, but I did not see a single Bembex there, although the donkey 

 was kept under observation for several hours. 



"The w^asps were thus exclusively frequenting the limits of the longipalpis 

 area. I searched in vain for their nests, the ground being uniformly covered 

 with dense vegetation, without any bare sandy patches suitable for their 

 colonies." 



The author attempts to explain the restriction of the wasps to the 

 longipalpis area by the suggestion that they were attracted by the smell of 

 the hippopotamus and antelopes which frequented this area, but not the 

 palpalis belt adjoining the river. The explanation can hardly be regarded as 

 satisfactory, for more than one reason. But in any case, the data are quite 

 inadequate to justify any conclusions on the subject. To mention a single 

 point. We need to know something as to the time of day and the weather 

 conditions of the experiment ; for the observations of the Peckhams on the 

 North American Bembex spinolce show that it never works more than 

 4 or 5 hours a day, and then only if the sun is shining (' Instincts and Habits 

 of Solitary Wasps,"* p. 62). With regard to Roubaud's inability to find the 

 nest of his Bembex, we may recall Bates'* statement concerning Monedida 

 sigtiata, a KSouth American species of similar habits, that it had to go 

 " at least half a mile " from its nest in order to reach its hunting grounds 

 (' Naturalist on Amazons,^ p. 182). 



It would be useful to have some more exact observations as to whether 

 the presence of the Bembex produces any a})preciable diminution in the 

 numbers of the Glossina. 



