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DESTRUCTIVE INSECTS. 



spray then, and every member of the first brood that is killed 

 greatly reduces the numbers of the following broods. In 

 badly infested pear-orchards it would pay to drench the bark 

 of the trees in winter with a spray of whale-oil soap, dissolving 

 about one pound in two or three gallons of water, and to each 

 hundred gallons of this add ten gallons of crude petroleum. 

 With this spray, o- with a kerosene-water pump, using 30 or 



FlG. 249. -The Pear Slug, a, Adult saw-fly; , slug with slime removed; 

 c. same in normal state ; rf, infested leaves, natural size ; a, b, c, much enlarged. 

 (U. S. Div. of Entomology.) 



40 per cent, of kerosene, most of the hibernating psyllas could 

 be killed, and thus the pest be checked for the coming season. 

 The nymphs and many of the adults can be killed in summer 

 by thorough work with a spray of whale-oil soap, one pound 

 in five gallons of water, or with a kerosene- water pump, 

 using about 10 or 15 per cent, of kerosene. Sometimes the 

 nymphs become covered with honey-dew, and it is difficult to 

 hit them with a spray. Hence, just after a hard shower is a 

 good time to make the application, as much of the honey-dew 

 will be washed off. Prompt and thorough work in May or 

 early June on the first brood is necessary if one is to control 

 this pest. It is a very difficult matter to check it if it is let 

 alone until later in the season. 



The Pear or Cherry Slug (Eriocampoides limacina). This 



