Indications concerning the flight activity of tsetse flies (Glossina morsitans Westw.) in the field

The content of proline, alanine and glutamate in the thorax of tsetse flies (Glossina morsitans Westw.) caught by two different sampling techniques is compared. Flies caught on a stationary bait animal have significantly less proline and significantly more alanine and glutamate than flies caught on a fly-round. The difference suggests that flies of the bait sample have been more active than flies of the fly-round sample during the period immediately preceding capture.