119 



" When a dragonfly has appeared at such times as there happened 

 to be no tsetses about," continues Dr. Lamborn, " further light as to 

 the object of its presence has been obtained from time to time by 

 flicking off one's hand a tsetse with one wing clipped. So fleet are 

 they on the wing that in a number of cases the tsetse was seized 

 before reaching the ground. By this method it was ascertained that 

 tsetse-flies-, whether half starved or replete with freshly ingested blood 

 (either from a goat or fowl), were equally acceptable to the dragonfly, 

 and after eating a replete tsetse the dragonfly has been found to have 

 the blood smeared abundantly over its face and jaws. The insect 

 is indefatigable in its work, and both sexes are to be found on the move 

 in glades, in open grass country, and on rocky barren soil far from water, 

 whether early or late, in sunshine or bad weather. The females feed 

 and oviposit readily in captivity, the eggs, which are numerous, being 

 arranged in irregular masses. 



" I have kept a look-out to determine whether any other species of 

 dragonflies habitually prey on tsetses. Only one other instance 

 occurred, and in this case the insect (Crocothemis erythraea, Brulle) 

 handled the tsetse-fly so clumsily, gradually slipping down and right 

 round the grass stem to which it was clinging, in a vain endeavour to 

 hold its prey and support itself at the same time, as to convince me 

 that it was quite a novice with tsetses." 



According to Simpson (144), in the Gold Coast, although some spiders 

 and dragonflies have been seen devouring Tsetse, " by far the most 

 important insect enemies are Asilid flies and wasps of the genus 

 Bembex," the former preying chiefly upon G. tachinoides, the latter on 

 G. morsitans form submorsitans. The Asilids in most cases were observed 

 to seize their victims on the wing. " The Bembex does not alight, 

 but darts quickly down and either captures the tsetse on the wing or 

 immediately it "has alighted/' To some extent the activities of 

 Bembex may neutralise those of Asilids, for Barker (8), after studying 

 a series of predacious insects and their prey in the Durban Museum, 

 records a species of Bembex as preying, not only upon G. morsitans, 

 but also upon seven species of Asilids ! 



Swynnerton (145), with reference to North Mossurise, Portuguese 

 East Africa, writes : " Dragonflies on several occasions in fly country 

 inspected the backs and necks of my companions. A wasp once did 

 the same. On one occasion, travelling from the Buzi to the Mtshanedzi, 

 five brevipalpis were under the cattle, four being under the leading ox. 

 We ran into some dragonflies, which at once began passing to and fro 

 immediately under the belly of that ox. I saw no captures, but these 

 four brevipalpis had disappeared when the dragonflies left us . ^ . 

 Dragonflies were exceptionally and extraordinarily numerous in 1918, 

 but the tsetse population remained large. I do not remember seeing 

 any Asilidae." 



CHAPTER XIII. 



MEANS OF LIMITING AND DESTROYING TSETSE-FLIES continued. 

 PARASITES OF TSETSE-FLIES. 



The parasitic enemies of Tsetse-flies may be divided into two cate- 

 gories parasites of the pupae, and external and internal parasites 

 of the adult flies. 



PARASITES OF TSETSE PUPAE. In the following pages we give a 

 statement of present knowledge as to parasites of Tsetse pupae, all of 



