284 GNATS OR MOSQUITOES — CHAPTER XII 



As already pointed out, malaria is limited not entirely by the 

 existence or otherwise of Anopheletcs , but also absolutely by 

 conditions of climate outside which the parasite is unable to 

 live; but the large material now to hand shows that where 

 climate is suitable, Anopheletes and malaria are generally found 

 together. On this point Mr. Theobald, in the Monograph, 

 writes : — 



"Professor Nuttall tells me that in England the distribution of A. 

 maculipennis and A. hifwrcatus compares exactly with the old dis- 

 tribution of ague. At the same time Anopheles occur in districts 

 where no ague has existed. 



" In those countries where malarial fever is rife the collections of 

 Mosquitoes received by the Museum have always contained many 

 Anopheles, with one notable exception, namely Victoria. For instance, 

 they occur in very large numbers on the West Coast of Africa, in 

 Central Africa, in large numbers in the Malay Peninsula, iji the West 

 Indies, and in India. On the other liand, in such parts as Brazil and 

 the Argentine, even along the swampy borders of the large rivers, 

 malaria is not very prevalent. Anopheles here, as far as observations 

 go, and records that I can find, are far from common, although other 

 Mosquitoes are a great scom-ge. 



" It does not of course follow because Anop>heles are present that 

 malaria is present, but where the latter occurs Anopheles have m all 

 cases but one been shown to exist in numbers. Amongst the small 

 collection of Mosquitoes sent from Victoria no Anoptheles are included, 

 but a series of Cidex tceniatus bears a label, ' abundant in the 

 malarious districts of the uplands of Victoria.' Four species of 

 Anopheles, however, occur in Australia, and may have been overlooked 

 in this colony, particularly as the collection only contains three species, 

 whicli number would probably be greatly increased on a further examina- 

 tion of the district. From Mauritius, where malaria is rife, the coUect- 

 tion only contained a few poor specimens of Culex, but three species 

 of Anopheles occur in abundance, one species particularly along the 

 coast, where the fever is most prevalent." 



A good deal has been written as to whether the bite of these 

 Mosquitoes is painless or otherwise, and as to whether they 

 " sing " or not, the opinions expressed being most contradictory. 



That Anopheletes " sing " I think there can be no doubt, for 

 the simple reason that the sound made by Mosquitoes of all sorts 

 is due to no voluntary effort of any sort on the part of the insect, 

 but is an inevitable, though accidental, necessity of the fact, that 

 owing to the peculiar character of their flight, their wings are 

 kept vibrating at a certain number of strokes a second, and hence 

 must produce the musical note corresponding to it. Where, as in 

 most of the larger insects, this rate is a low one, we hear the 



