Insect and Disease Control 245 



orchards. Though slight injury to the trees sometimes 

 follows, it may be reduced to a negligible degree by treating 

 only those trees that are known to be infected with this 

 insect. The slow dissemination of the insect from tree to 

 tree makes such a procedure practicable. 



The Bureau of Entomology ^ has reported some promising 

 preparations, one of the best of which is a linseed oil emul- 

 sion. Its preparation and use are described in the section 

 on insecticides (pages 283-284). 



Peach- and plum-slug (Caliroa [Eriocampoides] 

 amygdalina) 



For some years this insect has been observed in certain 

 localities in the South, where it sometimes causes serious 

 defoliation of peach trees. 



Appearance. 



The adult is one of the "saw-flies" which are small, trans- 

 parent-winged insects, commonly with bodies about ^ inch 

 long and with a wing expanse of about \ inch. In the 

 larval or "slug" stage, in w^hich it causes injury, it is indis- 

 tinctly pear shape, the body tapering from the head back- 

 w^ard. When fully grown, the slug is about f inch in length, 

 of a greenish color, and covered with slime. 



Life history and habits. 



The adult appears in early spring and begins laying eggs on 

 the foliage. The eggs hatch in about five days. The larva 

 or slug feeds on the under side of the leaves, eating all the 

 tissue between the veins except the upper epidermis. The 



1 U. S. Dept. of Agr. Bull. 351. 



