28 



that the secretion is protective against such ants as are usually found in 

 breeding places. It is probable also that it is of material advantage 

 in protecting the delicate cuticle from injury as the larva makes its 

 way down to its future resting place in the soil." 



Our faith in Dr. Lamborn's conclusion as to the protective value of the 

 secretion is, however, somewhat shaken by his admission that a small 

 Ponerine ant, Euponera senaarensis, Mayr, " on several occasions 

 uncompromisingly seized the larva and ran off with it." The possi- 

 bility that the true or main purpose of the secretion is to assist partu- 

 rition does not seem to have occurred to any observer ; should this be 

 the case, however, the viscid fluid would naturally be secreted by the 

 oviduct of the mother, and not, as Kinghorn supposes, by the larva 

 itself. It should be added that Simpson, who, in the Gold Coast, 

 tested the behaviour of eight different species of ants towards pupae 

 of G. morsitans form submorsitans, accepts Lamborn's inference 

 quoted above. " After prolonged observation," he writes (144), 

 " I agree with Lamborn that the viscid fluid around the larva is a 

 protection against carnivorous enemies. The ants approached them, 

 but backed away quite hurriedly before even touching them." 



Similar details to those furnished by Kinghorn, in the case of the larva, 

 of G. morsitans, are given by Stuhlmann, with reference to the larva 

 of G. brevipalpis. " If," writes the German observer, as quoted by 

 Austen, " the new-born larva be placed in a glass dish or on blotting- 

 paper, it crawls about for a time exactly like an ordinary fly-maggot, 

 after which it becomes stationary and soon contracts, its chitinous 

 integument thickens and darkens, and in about three-quarters of an 

 hour it has assumed the appearance of a ' coarctate ' pupa. If, 

 however, the larva be transferred to moderately damp sand, it at once 

 burrows into it, making a straight tunnel ; thus in one case a larva 

 penetrated to a depth of 8- 5 cm. (3Jin.). Under such conditions, 

 from an hour and a quarter to an hour and a half elapsed before the 

 change to the pupal stage was completed. In dry sand a larva did 

 not burrow so deeply, since, as it burrowed, the sand continually fell 

 in, but nevertheless it reached a depth of from 2 to 3 cm. (f to 1 in.). 

 We may assume that in nature the larvae behave in a similar way ; 

 the fly will deposit its offspring on a spot which is sheltered and slightly 

 damp, and the larva will at once burrow beneath the surface." 



According to Croveri (35), whose observations were made in Italian 

 Somaliland, the larva of G. pallidipes, on being extruded, immediately 

 seeks shelter, and in the laboratory was found to burrow into sand to 

 a depth of about three-fifths of an inch. 



PUPA. The pupa- case, or puparium, of a Tsetse-fly, which is com- 

 monly spoken of as the pupa, although the actual pupa lies within, 

 is more or less regularly ovoid in shape, and varies in colour from dark 

 reddish-brown to clove-brown, or dull blackish-brown, with the 

 exception of the tumid lips, which are jet-black. 



The integument of the pupa (puparium), like that of the larva, is 

 finely mammillated, or in other words, of a shagreen-like texture. 

 " The tumid lips seen in the larva are equally conspicuous in the pupa, 

 and the shape of the notch between them, in conjunction with the size 

 and shape of the lips themselves, affords a valuable means of identifying 

 and distinguishing pupae belonging to different species " (Austen. 

 See Fig. 5, p. 30). 



