46 THE INSECT WORLD. 



nothing else than dried earth, from which the stomach and intestines 

 of the insect have withdrawn all nourishing matter.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 Tipidce. often lay their eggs. Reaumur frequently found the 

 larvae in the trunks of elms or willows, and also in the fleshy parts of 

 certain kinds of mushrooms. He carefully observed the habits of 

 one, which lived under the covering of a mushroom, the Oak agaric 

 {Agaricus qucrciniis). 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. Gue'rin-Meneville has published some very interesting remarks 

 on the migrations of the larvae of a particular kind of Tipula, known 

 by the name of Sciara. 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 

 larvae are without feet, hardly five lines in length, and about the 

 third of a line in diameter. They are composed of thirteen seg- 

 ments, 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 

 larvae, formed by the union of an innumerable quantity fixed to each 

 other by a sticky substance. These collections of larvae resemble 

 fjome sort of strange animal of serpent-like form, several feet long, 

 one or two inches in thickness. Although clinging to each other by 

 thousands, they move onwards together. The whole society advances 

 thus with one accord, leaving a track after it on the ground, as a 

 material indication of its presence, and affording one of the most 

 singular spectacles that the eye of man has ever beheld. 



These strange collections of living creatures form societies, some- 

 times only a few yards long ; but at other times it happens that they 

 form bands from ten to twelve yards in length, of the breadth of a 

 hand and the thickness of a thumb. M. Guerin-Me'neville observed 

 columns as many as thirty yards in length. These troops advance 

 as slowly as a snail, and in a certain direction. If they encounter an 

 obstacle — as a stone, for instance — they cross over it, turn round it, 

 or else divide into two sections, which reunite after the obstacle is 

 passed. If a portion of the column be removed so as to divide it 

 into two parts, it is quickly reunited, as the hindmost portion soon 

 joins that which precedes it. Lastly, if the posterior part of thi? 



