Observations on laboratory colonies of the tsetse flies Glossina morsitans West. and Glossina austeni Newstead

Abstract

(a) Glossina morsitans1. A method of maintaining a breeding colony is described. The flies were best kept singly in tubes.2. The optimum temperature and humidity ranges were 74–80° F. and 60–75% R.H., respectively. Young flies failed to tolerate a lower minimum temperature.3. A light intensity of at least one foot-candle was needed at the feeding site.4. The method of feeding the flies was of prime importance. Best results were obtained by offering food every fourth day, at a temperature of 80–81° F. The best feeding animal was sheep, but guinea-pig was useful for inducing newly emerged flies to feed. The condition of the skin at the feeding site was important, and it is suggested that frequently changing the feeding animal will lead to better feeding.5. Female flies lived longer than male flies, and in both sexes the highest mortality was during the first 20 days of life.6. The optimum age for mating was 10–14 days for males and 3–4 days for females; 90–100% of the first and second generation females were fully inseminated.7. Each generation was less virile than the preceding one. Pupa production was decreased and the abortion rate increased from each generation to the next. Pupal viability, however, remained constant throughout all generations but the mean pupal weight showed a progressive decrease, except for the pupae from the second and third generation flies.8. The mean interval without food during an interlarval period did not affect the duration of the period.9. Feeding on the day of parturition did not significantly affect the length of the succeeding interlarval period.10. The duration of an interlarval period was directly correlated with the length of the maximum interval without food during the period.(b) Glossina austeni11. A colony was maintained in a manner similar to that used for G. morsitans, but best results were obtained at 80–85° F. and 77–82% R.H.12. Feeding was more satisfactory than in G. morsitans.13. In longevity and reproduction the flies were superior to G. morsitans.