358 The Principles of Fruit-growing 



Scab. — Very similar to apple-scab and demanding similar 

 treatment. 



Midge (Diplosis pyrivira). — ^A minute mosquito-like fly; lays 

 eggs in ilower-buds when they begin to show white. These 

 hatch into minute grubs which distort and discolor the fruit. 

 New York and eastward. Prefers the Lawrence. Introduced 

 ia 1877 from France. 



Not controlled by spraying. Destroy the infested pears. 

 Cultivate and plow in late summer and fall to destroy the 

 pupae then in the ground. 



Peak-Lbaj' Blister-Mite (Eriophyes pyri). — ^A minute mite 

 which causes black blisters to appear upon the leaves. The 

 mites collect under the bud-scales in winter. 



Lime-suKur or miscible oil as a dormant spray. 



Peak Psylla (Psylla pyricola). — These minute, yellowish, flat- 

 bodied, sucking insects are often found working in the axils of 

 the leaves and fruit early in the season. They develop into 

 minute, cicada^like jumping hce. The young psyllas secrete 

 a, large quantity of honey-dew, in which a pecuUar black 

 fimgus grows, giving the bark a characteristic sooty appear- 

 ance. There may be four broods annually, and the trees are 

 often seriously injured. 



Clean culture; remove rough bark from trunks and larger 

 branches to discourage adults from hibernating; spray with 

 "black leaf 40" tobacco extract, one pint in one hundred 

 gallons of water, adding four pounds soap, on warm days in 

 November or April, to kiU hibernating adults. Spray with 

 lime-sulfur, winter strength, when the blossom clusters 

 appear, to destroy eggs. 



In summer, spray with "black leaf 40" tobacco extract 

 just as the last of the petals are falling, to kill young. Repeat 

 if necessary. 



Pear Thbips (Euthrips pyri). — Minute insects one-twentieth 

 inch in length, dark brown when adult, white with red eyes 

 when young, that attack the opening buds and young fruits in' 

 early spring. They suck the sap from the tender growth, and 

 the females lay eggs in the fruit-stems, causing a loss of the 

 crop. The nymphs hibernate in the ground a few inches 

 from the surface. A serious pest in CaUfomia, and recently 

 introduced into New York. 



