384 



PEAR GROWING IN CALIFORNIA. 



of Tehachapi this pest occurs commonly. It is particularly bad in some 

 of the nonirrigated orchards of the Sierra Nevada Foothill and Moun- 

 tain Region and of the Northern California Coast Region. Affected 

 trees may be so stunted that they are not half as large as they should be 

 for their age, thus seriously interfering with their production. 



Control. 



Little can be done to rid affected trees of this pest after they have 

 been set in the orchard. Preventive measures consist of fumigation 

 with Formula No. 19 before the trees are planted. 



FIG. 176. 



Large pear tree showing injury from an abundance of root aphis, 

 Eriosoma pyricola. 



PEAR SLUG (Caliroa cerasi). 



One of the most commonly distributed pests of the pear and one that 

 is not lacking in importance where orchards are not sprayed with 

 arsenicals is the little deep green slimy larva which devours the upper 

 surface of the foliage. Not infrequently, where no control measures 

 are used, this insect completely defoliates the trees. In California, 

 where spraying is generally practiced for codling moth, orchards that 

 have come into bearing are not troubled, while young trees which do 

 not require an arsenical spray for codling moth are frequently badly 

 damaged. 



The adult insect is a little black, two-winged fly, which to the ento- 

 mologist is known as a sawfly. By means of a small, saw-like ovipositor, 

 from which this family of insects derives its name, the female prepares 

 a semicircular slit in the upper surface of a leaf, depositing an egg in 

 this slit just beneath the epidermis, resulting in a blister-like blemish. 



160 



