Twowinged Insects 



731 



HORNET ROBBER-FLY. 



Common in the south of England. 



r its rain-water butt. The females of some species construct 



small rafts of eggs, which float about on the surface of the 

 water till hatched, and then produce small maggots with a 

 breathing-apparatus at the end of the tail. In this condition 

 they swim head-downwards, while the more compact pupa 

 floats head-upwards. They may be destroyed by pouring a 

 little kerosene into their breeding-places; and as this floats 

 on the surface of the water, it does not interfere with the 

 use of the water in water-butts, which is usually drawn off 

 by a tap below. The males of gnats often have feathered 

 antennae and long, slender legs. The females, however, are 

 more nocturnal in their habits, and come into houses in the 

 evening, and keep people awake by their humming and pain- 

 ful "bites," or rather punctures, which frequently cause a 

 distressing irritation for a day or two afterwards. What is worse is that they are now 

 known to disseminate various diseases, such as elephantiasis and also malarial fever of every 

 kind, in this manner from the comparatively mild ague of the English fens (now nearly 

 extinct) to the terrible malaria of Southern Europe, India, and Africa, formerly attributed to 

 the unhealthy atmosphere of marshy countries, or to exposure to the night air in warm 

 countries, but now known to be caused by the bites of the gnats, or mosquitoes, which breed 

 in swampy places, and fly about in the evening. It is believed that only certain species of 

 gnats convey the germs of these diseases ; 

 and it has been stated that, though ague- 

 bearing species of gnats are still found in 

 England, those which have been examined 

 for the purpose have been free from these 

 germs, and are therefore incapable of propa- 

 gating the disease. 



In many parts of the world gnats are 

 excessively numerous and troublesome at 

 certain seasons of the year, filling the air 

 like clouds of dust, so that it is difficult 

 to sleep or eat from the annoyance and 

 irritation caused by their attacks. This 

 will be readily credible to those who have 

 experienced the pain which they cause even 

 when not very numerous, and have been 

 kept awake at night by their shrill piping 

 as they approach. They appear to be 

 equally numerous in cold and warm 

 countries Lapland, France, South Eussia, 

 Italy, various parts of America, and in fact 

 most parts of the world being liable to the 

 inordinate multiplication of different species. 

 In England they were formerly so 

 abundant in the fenlands that mosquito- 

 curtains were in use less than a century 

 ago, and may be so still. But their numbers 

 have so diminished of late years that, when- 

 ever gnats are a little more troublesome ~pk~otobyw. P. Dando~ F.Z.S.} ~ (Regent' Park. 

 than usual, it is reported that there has DADDY-LONG-LEGS. 



been an invasion Of mosquitoes. A year Or Large species, with variegated wings. 



