52 THE INSECT WORLD. 



M. Guerin-Meneville is of opinion that these larvae, which 

 exist in great numbers in certain districts, sometimes devour 

 all the nutritive substances contained in the ground. After 

 having done so, they are obliged to come out of it, in order to 

 seek at a distance a place where they will find food, or perhaps 

 only a suitable place to undergo their metamorphosis. It is then 

 that this singular journey commences. As regards the uniting of 

 these myriads of individuals into columns, M. Guerin-Meneville 

 thinks that it can be explained by the necessity these insects feel 

 for mutual protection against the drying effect of the atmosphere 

 when they are forced to leave the ground. United into masses, 

 and moistened by the glutinous matter which connects them, they 

 can leave their former place of abode without danger ; if each 

 were by itself, they would soon perish. Here, as in other cases, 

 union is strength ; and the strength of these larvae lies in this 

 protecting moisture. However it may be explained, the migrations 

 of these troops of insects are among the most astonishing pheno- 

 mena of nature. 



BRACHYCERA. 



The Brachycera, from ftpayyc, "short," and itepac, "a horn," 

 those Diptera having short antennae, are divided into four groups. 

 In this subdivision the sucker is composed of six bristles. Amongst 

 other families it includes that of the Tabanidtz, the insects 

 belonging to which family are of remarkable strength, and pos- 

 sessed of daring and courage in the highest degree. Their 

 wings are provided with powerful muscles, their feet are very 

 strong, and their trunk is provided with six flat, sharp lancets. 

 Distributed over the entire world, their instinct is everywhere 

 the same : it is the desire for blood, at least in the females, for 

 the males are not so warlike. They do no harm, but live on the 

 juices of flowers. They are chiefly found in woods and pastures, 

 and, during the hottest part of the day in summer, may be seen 

 flying about, seeking for their prey. 



M. de Saint-Fargeau has described the manner in which the 

 males fly. They may be seen flying hither and thither in the glades 

 of woods, remaining for some time suspended in the air, then dart- 



