

50 THE INSECT WORLD. 
Réaumur saw large districts of grassy swamps in Poictou which 
in certain years furnished very little grass for the cattle, on 
account of the ravages caused by these larve. They had also 
much injured the harvest in the same districts during those 
years. 
These larva appear to require no other food than vegetable 
mould. Their excrements are, in fact, according to Réaumur, 
nothing else than dried earth, from which the stomach and intes- 
tines of the insect have withdrawn all nourishing matter. 
Old trees have often hollow cavities occasioned by the decay 
of the trunk. When these cavities are old, their lower parts 
are full of a sort of mould which is in fact half-decayed wood. 
It is there that the Tipule often lay their eggs. Réaumur fre- 
quently found the larve in the trunks of elms or willows, and 
also in the fleshy parts of certain kinds of mushrooms. He care- 
fully observed the habits of one, which lived under the covering 
of a mushroom, the Oak agaricus. This larva is round, grey, 
and resembles an earth-worm. It does not walk, but crawls; 
and the places where it stops, or which it passes over, are 
covered with a sort of brilliant slime, like that left by the snail 
or slug. | 
M. Guérin-Méneville has published some very interesting re- 
marks on the migrations of the larve of a particular kind of 
Tipula, known by the name of Scara. We will borrow from that 
entomologist the following curious details, which will initiate us 
into one of the most wonderful phenomena in the whole history 
of insects. These small larve are without feet, hardly five 
lines in length, and about the third of a line in diameter. 
They are composed of thirteen segments, and have small black 
heads. 
In some years, during the month of July, may be found on the 
borders of forests in Norway and Hanover, immense trains of these 
larvee, formed by the union of an innumerable quantity fixed to 
each other by a sticky substance. These collections of larvee 
resemble some sort of strange animal of serpent-like form, several 
feet long, one or two inches in thickness, and formed by the union 
of an immense number, which cling to each other by thousands, 
and move on together. The whole society advances thus with one 
