500 THE APHIS OF THE ROSE-TREE. 



tender part, but because it affords them protection from the weather, 

 and from various injuries to which they would otherwise be exposed. 

 Sometimes, though rarely, the root is the object of their choice; and 

 ihe roots of lettuces have been observed so thickly beset with one of 

 the species, that a whole crop has been rendered sickly and or* little 

 value. They are rarely to be found on the bark of trees. 



The Aphides afford another surprising deviation from the general 

 laws of nature ; one impregnation of the female is sufficient for nina 

 generations. 



THE APHIS OF THE ROSE-TBEE. 



This insect, which is well known by the name of Rost Louse, ia 

 generally of a green color, with the tip of the antennae and horns black. 

 The tail is pointed, and without a style. 



Towards the beginning of February, if the weather be sufficiently 

 warm to make the buds of the rose-tree swell and appear green, this 

 'species of Aphis will be found on them in considerable abundance. 

 They are produced from small, black, oval eggs, which were deposited 

 in autumn on the last year's shoots. If, after their appearance, the 

 season become cold, almost the whole of them suffer, and the trees, 

 for that year, are in a great measure freed from them. 



Those that withstand the severity of the weather, seldom arrive at 

 their full growth before April, when, after twice casting their skins, 

 they begin to breed. It then appears that they are all females; each 

 of them produces a numerous progeny, and that without any inter 

 course with a male insect. 



If the Aphides had not many enemies, their increase in summei 

 would sometimes be destructively great. 



After a mild spring, most of the species of Aphis become so numer 

 ous as to do considerable injury to the plants on which they are found. 

 The best mode of remedying this evil, is to lop off the infected shoots 

 before the insects are greatly multiplied, repeating the same operation 

 before the time that the eggs are deposited. By the first pruning, a 

 very numerous present increase will be prevented ; and by the second, 

 the following year's supply may, in a great measure, be cut off. 



OF THE COCCUS, OR COCHINEAL INSECTS. 



THESE are an extremely fertile race, and many of them are very 

 troublesome in stores and green-houses. The females fix themselves, 

 and adhere almost immovably, to the roots, and sometimes to the 

 branches, of plants. Some of them, having thus fixed themselves, lose 

 entirely the form and appearance of insects : their bodies swell, their 

 skin stretches and becomes smooth, and they so much resemble some 

 of the galls or excrescences, found on plants, as by inexperienced 

 persons to be mistaken for such. After this change, the abdomen 



