TWO -WINGED INSECTS 
333 
photo hy W, F, Dando^ F.Z.S^'] 
HORNET ROBBER-FLY 
Common in the touth of England 
is worse is that they are now 
and also malarial fever of every 
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 
known to disseminate various diseases, such as elephantiasis 
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 ; 
: ' 'l and it has been stated that, though ague- 
At; bearing species of gnats are still found in 
; England, those which have been examined 
for the purpose have been free from these 
i germs, and are therefore incapable of prop- 
agating the disease. 
; In many parts of the world gnats are 
excessively numerous and troublesome at 
■T; 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 
r. I equally numerous in cold and warm 
■p :; countries — Lapland, France, South Russia, 
; _ j Italy, various parts of America, and in fact 
P ■ j most parts of the world being liable to the 
; inordinate multiplication of different species, 
I In England they were formerly so 
: abundant in the fenlands that mosquito- 
■p j curtains were in use less than a century 
: Aj] ago, and may be so still. But their numbers 
EsL- have so diminished of late years that, when- 
ever gnats are a little more troublesome 
than usual, it is reported that there has 
been an invasion of mosquitoes. A year or 
Photo hy Dando^ F. Z. S, 
DADDY-LONG-LEGS 
Large species^ ^ith 'variegated wings 
22 
