PEAR GROWING IN CALIFORNIA. 



385 



In a few days' time this egg hatches into the characteristic slug-like 

 larva which immediately begins feeding. Their attack begins quite 

 early in the season, about May. Only the upper surfaces of the leaves 

 are fed upon, but sufficient tissue is removed so that they are killed 

 where excessive feeding takes place. The larvae, when full grown, 

 pupate in the soil and emerge as flies for a second generation after mid- 

 summer. The winter is spent in the pupal stage in the soil of the 

 orchard. 



Control. 



There are few pests that succumb to control measures as easily as 

 this one. As has already been stated, trees that are sprayed with lead 



FIG. 177. Eggs of pear slug, Caliroa cerasi. 



arsenate and other arsenical sprays are not injured, because of the 

 susceptibility of the larvae to poisoning by arsenicals. Ordinarily, one 

 spraying for the first brood will eliminate the trouble for a season. 

 Should a second be necessary it should be applied as the second brood 

 begins its attack. Spraying with "Black Leaf 40" or any other good 

 contact insecticide is just as effective as an arsenical in killing the larvae, 

 but has no effect on the eggs, consequently, when contact sprays are used 

 the dose should be repeated in a week or ten days' time. Dusting has 

 been used effectively in the control of pear slugs. Its effectiveness is 

 due to the sliminess of the larvae which causes the dust to adhere to 

 the surface of their bodies, eventually resulting in death either by 



167 



