MATERNAL INSTINCT IN MOSQUITOS 27 



dark, quiet corner of a mosquito-infested house. Into 

 one put some clean, filtered water, and into the other 

 put an equal quantity of dirty water in which, say, 

 the cook has washed the plates. Leave the buckets 

 for three days, and if the water in them is 

 then examined, numbers of mosquito eggs batches 

 and rafts will be found floating on the surface of 

 the dirty water, and few or none on the surface of 

 the clean water. The maternal instinct drives the 

 female mosquito of the domestic species to lay her 

 eggs where her larvae will thrive. 



Each separate egg gives rise to one mosquito larva 

 or wriggler. Each egg-raft or batch produces, there- 

 fore, a brood of swimming larvae. These small 

 aquatic insects are well known even in England 

 during the summer. If after a heat-wave the 

 water-butt in the garden is examined, hundreds 

 of these fish-like insects can usually be seen in the 

 water. They are worth watching. Note how they 

 avoid the direct sunlight, and keep to the shady 

 edges of the tub. Here they collect, their heads 

 hanging downwards, their tails touching the surface 

 of the water. When disturbed, they wriggle down 

 to the bottom of the water. They feed on such 

 minute, living or dead, animal or vegetable particles 

 as they can find. 



The Culex larva differs slightly from the Stego- 

 myia ; the former, when resting near the surface of 

 the water, is nearly perpendicular to it, the latter is 

 at an acute angle to the surface. The Culex larva 

 possesses a long tube in its tail through which it 



