206 MALCOLM E. MACGREGOR. 



Anopheles maculipennis. 



Normal conditions. — As larvae and pupae ; plentiful in farm ponds and small 

 lakes from end of March until October. As adults ; very numerous in pigsties 

 throughout the spring and summer months. Hibernating females common during the 

 winter months. 



Conditions during drought. — As larvae and pupae ; numbers relatively reduced 

 owing to dr3dng up of many normal breeding-places ; but in certain permanent small 

 lakes, actual numbers of larvae and pupae increased, probably on account of the 

 scarcity of available breeding-places. As adults ; plentiful but not actually numerous 

 in pigsties. 



It appears from my observations locally that Anopheles maculipennis is the 

 species least affected bj' the drought. It chooses as a favourite breeding-place the 

 shores of large and small natural ponds and lakes which are, of course, the last 

 waters to dr}^ up in conditions of drought ; and this species is consequently one of 

 the last to experience difficulty in obtaining breeding-places. 



I should mention that pigsties in this locality have been found to be the favourite 

 haunts of adult Anopheles maculipennis and Anopheles bifurcatus, and that these 

 mosquitos are rareh' found in stables. This state of affairs, which is so very different 

 from that in other parts of the country, is, I think, due entirely to the fact that all 

 the stables which I have visited in this county are ventilated at the junction of the 

 wall and roof. This method ensures a very thorough ventilation, and the average 

 temperature in the stables is much lower than the average temperature in stables 

 where ventilation is afforded by a few windows. Furthermore, because of the archi- 

 tecture, the amount of light in the average stable in Surrey is much greater than that 

 found in the average stable in Kent for instance, where Anophelines frequent the 

 stables in large numbers. This is a matter of such significance that attention should 

 be drawn to the value of the design in providing an " all-the-way-round " ventilation 

 between the walls and roof, as preventing the accumulation of mosquitos in stables. 



The local pigsties, on the other hand, are low-built and the contained atmosphere 

 is close and warm at all times of the year, so that very favourable conditions are 

 maintained for the accumulation of mosquitos when they seek a blood meal, and 

 also conditions favourable to the hibernating females during the winter. 



Anopheles piumbeus. 



Normal conditions. — As larvae and pupae ; found in almost every water-containing 

 tree-hole in a variety of different kinds of trees throughout the sunnner and winter 

 months. As adults ; seldom observed, but occasionally in association with 

 Ochleroiatus spp. they have shyly attacked me while I have remained quietly seated 

 in the woods. 



Conditions during drought. — As larvae and pupae ; unobtainable now for many 

 weeks (last captured about middle of May), as all water in tree-holes has completely 

 evaporated. As adults ; none observed since middle of May. 



Anopheles piumbeus in this locality is quite common as larvae in water-containing 

 tree-holes and, as usual, is often associated with the larvae of Finlaya geniculata. 



Very few adults have been observed, and the one or two that I have caught sight of 

 have eluded capture. I have been anxious to obtain adult females for some time, 

 so as to get ova for the completion of certain observations. It occurred to me that 

 possibly another way of obtaining ova would be carefully to clear of detritus one of 

 the tree-holes in which Anopheles piumbeus had been breeding, and to keep it filled 

 with water artifically. Unfortunately this plan did not succeed, as such hosts of 

 insects regarded it as a providential water-supply when water was difficult to obtain 

 that the entrance to the hole was constantly choked with a seething mass of thirsty 

 insects. 



