38 THE INSECT WORLD. 
those genera of Diptera which are composed of insects on some 
account remarkable. 
M. Macquart, the learned author of “ L’ Histoire Naturelle des 
Diptéres,”’* divides this great class of insects into two principal 
groups. In one of these groups, the antenne are formed of at 
least six joints, and the palpi of four or five: these are called 
Nemocera. In the other, the antennz consist only of three joints, 
and the palpi of one or two: these are the Brachycera. 
The Nemocera may generally be distinguished from the other 
Diptera, independently of the difference in the antenne and palpi, 
by the slenderness of the body, the smallness of the head, the 
shape of the thorax, and the length of the feet and wings. The 
result of this organisation is a graceful, light, and aerial form. 
NEMOCERA. 
Abounding everywhere, the Nemocera live, some on the blood 
of man and animals, some on small insects, and others on the 
juices of fragrant flowers. 
In all climates, in every latitude, in the fields and woods, even 
in our dwellings, they may be seen fluttering and plundering. 
The Nemocera are divided into two families, that of the Culicide, 
of which the gnat (Culex), which has a long, thin trunk, and a 
sucker provided with six bristles, is a member; and that of the 
Tipulide, which have a short, thick trunk, and a sucker having 
two bristles. 
We will begin our examination with the Gnat (Culex pipiens), 
of which Réaumur, in his “‘ Memoires pour servir a. l’ Histoire des 
Insectes,” has given such a curious and complete history. ‘‘ The 
gnat is our declared enemy,” says Réaumur, in the introduction 
to his memoir, “and a very troublesome enemy it is. However, 
it is well to make its acquaintance, for if we pay a little attention 
we shall be forced to admire it, and even to admire the instru- 
ment with which it wounds us. Besides which, throughout the 
whole course of its life it offers most interesting matter of 
investigation to those who are curious to know the wonders of 
nature. During a period in its life the observer, forgetting that 
* “Suites 4 Buffon,” 2 vols., 8vo. 
