408 ANNUAL KEPORT OF THE Off. Doc. 



in the egg state, and hatch about the time the buds open in the 

 spring. Each is then a tiny insect with six legs and no wings, which 

 crawls about and sucks the sap from the plant on which it is by 

 means of a sharp-pointed beak which it thrusts through the bark 

 or epidermis of the plant till it reaches the sap. In the course of a 

 few days it becomes adult and begins to produce young, giving birth 

 to three or four a day. These young also become adult in a few days 

 and in their turn produce young, and in this way there may be many 

 generations during the summer. Some one or more of these genera- 

 tions will develop wings and pass to the other plants, thus distribut- 

 ing the insects over the region. In the fall some generation instead 

 of giving birth to young, will lay eggs, and these will winter over and 

 hatch the following spring. 



Treatment. 



As plant lice are sucking insects, no stomach poison such as Paris 

 green or arsenate of lead is of any value to destroy them, and kero- 

 sene emulsion is the most effective remedy made use of. In order 

 to kill the lice, however, every insect must be touched by the oil and 

 this requires careful and thorough spraying. As the lice are usua'ly 

 on the under surface of the leaves the spray must be thrown upward 

 against the lice, and after the leaves begin to curl this is very diflQ- 

 cult if not impossible. It is necessary, therefore, that the trees 

 should be carefully watched, and be sprayed as soon as the lice ap- 

 pear, and before they have become so abundant as to cause the 

 leaves to begin to curl. 



In places where it can be obtained, a strong stream of cold water 

 thrown through a hose upon a tree infested with plant lice, is very 

 effective as it knocks the lice off the tree and kills nearly all of them, 

 but too often this treatment is not available. 



In the case of the pea-vine louse, the peas grow in such a way that 

 it is difficult to reach the lice by spraying, and here the best practice 

 is to follow along the rows on a hot day with a branch from some 

 evergreen tree, or a piece of brush, and switch the lice off the vines 

 onto the ground, which can be easily and rapidly done. A cultivator 

 should then follow along the rows and loosening the dry, hot soil, 

 the lice will be dried up by it and die before they are able to return 

 Jo the plants from which they had been switched off. 



