GLOSSINA INVESTIGATIONS IN NYASALAND. 257 



described, the parasite having in practically every case escaped at the cephalic end ; 

 107, roughly 1 per cent., were intact, except for a pin-point hole at one side, produced 

 in all probability by the escape of some tiny parasite, possibly a Chalcid parasitic 

 on the Mutillid, for a few of these which were broken open showed the remnant 

 of the cocoon of the latter ;* 264, roughly 2 per cent., show larger rounded holes 

 produced by the escape of a parasite, some at the posterior end, others to one side, 

 the insect being in all probability one of the large Chalcids. Some twenty, a few 

 of which had contained Mutillids, showed evidence that the pupal contents had 

 been eaten from outside ; and 477 were so damaged that it was impossible to form 

 any opinion as to their history. 



No parasites whatever have as yet been bred out from pupae obtained in the 

 proclaimed area,f all that have been obtained hitherto having emerged from pupae 

 found in the vicinity of Monkey Bay, a fact which may explain the numerical 

 superiority of morsitans in the former region. 



Breeding places. 



Until April the search for breeding places had been almost without result, five 

 pupae only having been found in hard clayey soil. But since then they have been 

 obtained in large numbers, as the result of realising that the condition of the soil 

 is one of the all-important factors in determining whether or not a particular spot 

 will be selected by the female. 



As pointed out by Mr. Lloyd, the fly seeks some relatively dark and shady spot. 

 Many such are to be found in a tsetse area, mostly under fallen trees ; but in my 

 experience, which is now considerable, being based on an examination of 512 breeding 

 places, few, if any, pupae will be found unless, in conjunction with the shelter, the 

 soil is likely to be dry at all seasons, having no hard top crust, such as is formed 

 under the influence of moisture and sun, and containing sand and decaying wood 

 or other vegetable matter so as to make it light. In nearly every instance the 

 breeding places have been situated beneath a fallen and well decaying tree, which 

 has been prevented by some of its limbs from actually touching the ground, and 

 is of such girth as to keep an area beneath it shaded and free from moisture. The 

 soil in such a place being leavened by humus becomes light and friable, so that 

 the larva can have little difiiculty in making its way into it. 



Very few pupae have been found in hard clayey soil beneath trees, and as it has 

 been found experimentally that the larvae have very weak boring powers, being 

 unprovided with bristles, their occurrence in such situations is probably purely 

 accidental, the parent fly having possibly failed to find a suitable place in time for 

 the birth of its offspring. Such soil, moreover, in the dry season dries almost as 

 hard as stone, needing such considerable force to break the top crust as would render 

 it almost impossible for the newly emerged fly to break its way to the surface. 



* [A large number of these Chalcids were bred subsequently by Dr. Lamborn from 

 a tsetse pupa and prov^ed to be Syniomosphyrum glossinae, Wtrst. Tliere seems little 

 doubt now that this species is harmful, being a hyperparasite of Muiilla glossinae. — Ed. J 



t [If this observation is confirmed, it may prove to be of considerable practical 

 importance, for the introduction of parasites from Monkey Bay would probably in that 

 case have a material effect upon the numbers of the fly in the proclaimed area. — Ed.] 



