Time of arrival of gravid Culex pipiens fatigans at an oviposition site, the oviposition cycle and the relationship between time of feeding and time of oviposition.

One of the most important activities in a female mosquito's life is the flight to the breeding place and the subsequent deposition of eggs. During this phase, motivated by endogenous and exogenous stimuli, the female is particularly exposed and susceptible to attack. It is therefore important to investigate these episodes in the gravid female's life.The work reported in this paper shows that gravid Culex pipiens fatigans females are easily trapped over breeding-water; there are two peaks in the arrival at a breeding site, one just after sunset and the other at sunrise. The oviposition cycle is biphasic, the two peaks coinciding, in calm weather, with the two arrival peaks; wind and rain cause marked disturbances in the oviposition cycle.The mean duration of the gonotrophic cycle depends on the time of feeding; this finding is of practical importance since the length of the cycle is often used to calculate the daily survival rate of adult mosquitos. It appears that oviposition is stimulated by a change in light: from light to dark for mosquitos ovipositing in the evening and from dark to light for those ovipositing in the morning.Apart from revealing some hitherto unknown behaviour patterns, the techniques evolved could also be used in the assessment of mosquito populations and hence the effects of control measures.