152 BOARD OF AGRICULTURE. [Pub. Doc. 



yielded a full crop, while the unsprayed trees were stripped 

 of leaves and bore no fruit. These trees were sprayed but 

 once, and this method appears to have been more effectual 

 and far cheaper than the others. In case of rain it might be 

 necessary to repeat the spraying, but even then it would be 

 the cheapest method. 



Plant Lice. 



Plant lice or aphids have been very abundant during the 

 past summer, not only on fruit trees but also on ornamental 

 trees and shrubs and in greenhouses. These insects have been 

 sent to me from all parts of the State, with letters request- 

 ing information as to methods of destroying them. There 

 is a very large number of species of these insects, and com- 

 paratively few of those in this country have been studied as 

 yet. They all have their mouth parts developed into a 

 sharp, piercing, sucking tube, which they force through the 

 outer covering of the leaves or twigs on which they rest, and 

 draw the sap from within. As these insects are very small, 

 a few would produce no appreciable effect upon the vigor 

 of the tree, but their powers of reproduction are so remark- 

 able that they multiply prodigiously. 



The last brood in the fall, almost without exception, con- 

 sists of males and females, and after mating the females lay 

 their eggs and then die. Early in the spring, as soon as the 

 sap begins to flow, these eggs hatch, and the young lice, 

 which are wingless females, at once insert their tiny beaks 

 into the bark or leaf on which they are resting and begin to 

 pump up the sap. They wander but little, but devote their 

 entire time to feeding, hence they grow rapidly and soon 

 reach maturity, when, without the intervention of males, 

 they give birth to their young alive, one at a time ; and in 

 some species a single female gives rise during her life to 

 one hundred or more young ones, each of which quickly de- 

 velops, and after reaching maturity gives birth to wingless 

 females ; and so on, generation after generation, till the cool 

 weather of the fall causes a change to take place, and the 

 last o;ene ration consists of males and females. These mate, 

 and the females lay their eggs, which remain on the trees 

 and hatch in the spring as before. 



