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ON WEST AFRICAN TRYPETID^ (FRUIT FLIES). 



., By W. M. aEAHAM, M.B., 

 Director of the Medical Eesearch Institute, Lagos. 



(Plates XL-XIII.) 



Toe family of the Trypetid^ is of great economic importance, for among 

 its numerous genera are to be found many pests of the orchard and farm. 

 The flies of this family are rarely brought to the notice of Europeans in AVest 

 Africa, for there farming operations are entirely in the hands of the native 

 population and the amount of damage done by thf^^se insects is perhaps 

 insufficiently appreciated by Europeans ; but from observations made in my 

 own gardens, during a long West African experience, I believe the loss caused 

 by their attacks must be considerable. The flies which are responsible for the 

 damage observed belong to two genera — Ceratitis, MacLeay, and Dacus, 

 Fabricius. 



Ceratitis, MacLeay. 



Small broad-winged flies, measuring from ^-^ to -^-^ inch in length. 



During life, the eyes of all the local species I have seen are bright emerald- 

 green, sometimes banded, and showing an iridescent play of colour. The wings 

 are hyaline and ornamented with a distinct jiattern of bands and spots, the 

 spots being usually found on the basal third of the wing. The flies are found 

 walking about upon the leaves or fruit of certain shrubs or trees, lazily 

 waving their partly extended wings. The yellow head, green eyes and lazy 

 movement of the wings make the flies remarkable objects. They cannot, 

 however, be identified from these distinctions alone, for some species of the 

 Ortalid^ resemble them in coloration and in the movements of the wings. 

 From these latter the species of Ceratitis may be readily distinguished 

 (among other characters) by the presence of four pairs of fronto-orbital 

 bristles, extending the whole length of the forehead, from the vertex to the 

 antennse. 



The female fly pierces the skin of the fruit with her ovipositor, and then 

 lays her eggs in the fruit-pulp, where they hatch and become larvae. The 

 larv8e are elongated cream-coloured maggots. About the time that the larvae 

 tire mature the infested fruit becomes rotten, and falls to the ground and 

 usually liursts. The mature larvae then leave the fruit, leap about upon the 



BULL. ENT. RES. VOL. I. PART 3, OCTOBER I9IO. P 



