INSECTS OF TIIE GREENHOUSE. 315 



of the body are considerably elongated, often being as 

 long as the body itself. The male undergoes a transfor- 

 mation, and covers itself with a thick cottony mass. It 

 is of a brown color, with long grayish wings. 



Another form, known as the Destructive mealy bug 

 {Dactylopius destructor), of a yellowish-brown color, 

 with seventeen short, stout, lateral appendages upon 

 each side of its flattened body, with a very thin waxy 

 covering. This form has been particularly destructive to 

 orange trees. The form known as D. longifilis differs 

 principally in having longer appendages, there being two 

 iu particular upon each side of the rear end of the 

 abdomen that are as long as the entire body. 



All of these forms of mealy bugs thrive in close, hot 

 and dry air, and particularly like to conceal themselves 

 in a corner or in a thick tangle of vines. The conditions 

 that favor their development should be avoided, and 

 where the plants can be reached a free use of the hose 

 with a powerful spray will often blow them off from 

 the leaves. Kerosene emulsion, where it can be brought 

 in contact with the mealy bugs, is also a powerful insec- 

 ticide, as is also fir tree oil and other commercial com- 

 pounds. On many stove plants, with large delicate 

 leaves, the use of a stiff brush and dilute kerosene emul- 

 sion, or whale-oil soap, is preferable. 



The genus Aspidiotus, to which a large number of 

 true scale insects belong, differs in lacking, in most spe- 

 cies, the waxy covering. They are of a yellowish or 

 brownish color. At first the larvae are active, but soon they 

 form a scale and fix themselves; after molting a number of 

 times they reach full size, when they are covered with a 

 thick, firm shell. Eggs are now deposited and, on hatch- 

 ing, the second brood starts on the road to development. 

 In some cases there are as many as five broods a year. 



Closely related to Aspidiotus, and often classed with 

 it, are such other genera as Diaspis, Chionaspis, Jidytila- 



