114 GNATS OR xMOSQUITOBS — CHAPTER VII 



Food then, alike for larval and adult insect must be 

 obtainable in close proximity. The pupa does not eat- 

 In the adult stage, the usual food of probably all species 

 of both sexes is the juices of plants, and although the 

 females of many attack and suck the blood of vertebrates, 

 food of this sort does not seem to be in any way essential to 

 their welfare, as most species will lay their eggs equally well 

 on a purely vegetable diet. Moreover, even in the case of 

 notoriously troublesome species, it is often difficult to induce 

 them to bite animals, although they will still feed on their 

 more usual vegetable food. A high atmospheric tempera- 

 ture appears to be the main determining condition of these 

 outbursts of sanguinary instinct, and this is probably the 

 reason why, in spite of gnats being quite common, we 

 are so rarely troubled by their attacks in England, for it is 

 noticeable that whenever there occurs a spell of excep- 

 tionally hot weather, we find in the press notices of an 

 invasion of England by Mosquitoes, which, however, always 

 turn out to be common indigenous species when submitted 

 to a competent entomologist. The same thing may be 

 observed in Northern India, where it will be found that 

 Mosquitoes cease to be troublesome, some time before they 

 have finally hidden themselves for their cold weather rest. 

 Speaking generally, only the females bite, and it is notice- 

 able that different persons differ greatly in their reaction to 

 the stings of these insects. When Mosquitoes are unable or 

 unwilling to obtain blood they suck the juices of plants. 

 They are frequently found on flowers, and especially in 

 England on the catkins of the willow. On hot days and in 

 places exposed to sunshine they remain at rest until the 

 evening, but especially in wooded localities they often are 

 active in the middle of the day, and may often be observed 

 perched on leaves and making a sort of balancing movement 

 of the body, by alternately bending and extending their legs 

 in the same way as do many of the Tipulidce. 



In India too, the most usual recognisable constituent of 

 the contents of the stomach, of all species I have examined, 

 in both sexes is pollen. Now some pollen grains look not 

 unlike the printed representations of zygotes, and I have 



