HEMIPTERA. 



117 



dark green colour, mixed with black. The wings are transparent, 

 and the upper ones are as long again as the body. The young shoots 

 of the elder-tree, all round their circumference for the length of 

 from a foot to a foot and a half, are often covered with black plant- 

 lice, or with those of a greenish-black colour. They are crowded one 

 against the other, and sometimes there are two layers of them. 



i^<^ 



Fig. 87, 88.— Winged Aphides, or Plant-lice (magnified). 



If observed without moving the plant about, they appear to be 

 tranquil and inactive. They are, however, then absorbing from the 

 plant the nourishment it should have ; piercing with the point of their 

 trunks the epidermis of the leaves or stalks, and drawing from them 

 a nourishing liquid. 



But this occupation is confined to those which are on the plant 

 itself Those which, on account of the enormous agglomeration of 



Fig. 89, 90. — Wingless Aphides, or Plant-Iice (magnified). 



these insects, walk, not on the branch, but on other plant-lice, and 

 cannot therefore suck the sap of the plant, are employed entirely in 

 preserving and multiplying their species. 



Re'aumur often saw the latter, easily recognised by their great 

 size, giving birth to little plant-lice, which are quite alive when they 

 leave their mother. The young ones set off and mount or descend 

 till they reach one end of the crowd, and there each takes up its 

 position, like a cardboard capuchin {capiicin de carte), in such a manner 



