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numbers, the laboratory output would necessarily be very limited. It 

 has occurred to the writer that it might be possible to employ as 

 alternative hosts the puparia of some of the common Muscids, then 

 liberating in great numbers the little insects, each with its dominant 

 aim in life to seek out and destroy the greatest of the insect scourges 

 of man and beast in the African Tropics. 



" The general upset of work as a consequence of war conditions made 

 any attempt to put the idea to a practical test impossible, but an 

 opportunity was made to carry out, during 1918 in East Africa and 

 during the last six months of 1919 in Nyasaland, research work in 

 regard to the question of alternative hosts for Chalcids normally 

 parasitic on certain Muscids. The results (which will be written up 

 later) showed some promise, though this work has again, unfortunately, 

 been brought to a premature close." 



Some very interesting suggestions have been made by Dr. E. Rouband 

 (122), as to the possibility of utilising for the control of Glossina the 

 Chalcid Nasonia brevicornis, Ashm., which is known to parasitise the 

 pupae of various Muscids throughout the world. In the course of an 

 investigation conducted by him in Paris, Dr. Roubaud succeeded in 

 inducing this parasite to oviposit in pupae of G. morsitans obtained 

 from an imported stock of Tsetse-flies, which he had been able to breed 

 in France for several years (see p. 159). Unfortunately the Tsetse 

 puparia proved to be too tough to allow the adult parasites to emerge. 

 Nevertheless it is considered by Roubaud that the destructive powers 

 of N. brevicornis in connection with the pupae of various flies, and its 

 perseverance in reaching and puncturing its victims, even when the 

 latter are concealed under a light layer of earth, indicate the possibility 

 of using this species in the campaign against Glossina, the pupae of 

 which are hidden under bark, in holes in trees, under light sand, etc. 

 As we have seen, a number of specific parasites of Tsetse-flies have been 

 described during the last few years, but their biology is at present too 

 little understood to allow of their being utilised to any great extent. 

 This cannot be said of N. brevicornis, which can be obtained in large 

 quantities from the pupae of common Sarcophagid flies. Under the 

 conditions of Roubaud's laboratory experiments, the mode of action 

 of the parasite towards the pupae of G. morsitans was the same as 

 towards those of French Muscids. Young pupae were searched for 

 eagerly, the old ones avoided. The development of the pupa of 

 Glossina being slower (one month) than that of Calliphora (Blow-flies) , 

 the possible limit of infestation of Glossina is naturally more extended. 

 The impossibility of emergence limits the extent of parasitism, although 

 it does not reduce the immediate destructiveness of the parasite. 



There naturally arises the question of the possibility of acclimatising 

 the insect. N. brevicornis seems experimentally capable of enduring 

 the usual temperature in which Tsetse-flies live ; at 77 to 82 F., 

 which is the average temperature of Glossina haunts, its life is 

 apparently normal, the activity of the adults being increased and the 

 life-cycle appreciably shortened. A female reared at this temperature 

 produced 105 individuals in 12 days. A greater difficulty is the 

 maintenance of parasitism in Tsetse breeding grounds, if the continuity 

 of parasitism at the expense of Glossina be impossible. Roubaud 

 thinks it probable, however, that the Chalcidid will find species of 

 Diptera other than Glossina in which successive generations can breed. 

 Experiments in this connection would be interesting, and as regards 

 disseminating the parasite among Glossina haunts no difficulty need 

 be apprehended. Having obtained a quantity of parasitised pupae of 



