The mortality of Aedes aegypti mosquitoes increased; (i) immediately following a blood meal containing microfilariae of Brugia pahangi, (ii) when infective larvae began to migrate out of the flight muscles and (iii) when infective larvae were lost from the mosquitoes during a blood meal. When infective mosquitoes took a second blood meal 86–2% of the infective larvae escaped from their bodies. However, only 50–3% escaped when mosquitoes fed through a thin layer of cotton. Infective larvae in the abdomen of the mosquitoes stood the least chance of escaping from the insects. When infective mosquitoes were offered a third blood meal four days later, the proportion of infective larvae in the head and labium had risen from 56–6% in the control group to 660% and 69–4% in the two test groups. At this third feed 54–7% and 75–7% of the infective larvae were lost from mosquitoes with a low and medium pre-feeding worm burden respectively. This suggests that the escape of infective larvae from mosquitoes with only a few worms is less efficient than from mosquitoes with a medium worm burden.
