448 Rkpokt of the IIohticultueist of the 



" oval cocoons of silk covered with grains of sand " (Smith.) This 

 probably takes place any time from early spring to mid-summer, 

 depending npon the locality, although in this State most of them 

 go into the ground in June. They remain as pupa: in the ground 

 all winter, emerging as adults in the spring. Lawrence pears are 

 especially liable to attack. 



Treatment. — This insect has proved a very difficult one to con- 

 trol. Experiments have been made with a view to destroying the 

 pupa; in the ground, but it has been found that in order to suc- 

 cessfully check the insect a dangerous amount of the insecticides 

 tested must be applied to the soil. Hand picking, where practical, 

 is probably the most satisfactory method of checking the insect. 

 It should be done in June. 



OYSTEE-SHELL BAEK-LOUSE. 



This insect also has been discussed under apples, page 417. It 

 is sometimes very injurious to young pear trees. 



PEAE PSYLLA. 



(Psylla pyricola Forst.) 

 Description.— This insect causes injury in two ways. First, by 

 sucking the sap ; second, by disfiguring trees and fruit. Its pres- 

 ence is usually betrayed by the honey dew secreted by the young, 

 wine-less forms. The honev dew afterwards becomes covered 



'fe 



Avith a ])lack mold giving the leaves and twigs a black unsightly 

 appearance. 



The adult is an active four-winged insect measuring about one- 

 tenth of an inch in length. It has been compared to a miniature 

 seventeen year locust. A number of broods are produced during 

 the summer, and the adults which live through the winter are 

 distinct in form from the summer adults. They appear early in 

 the spring and deposit their eggs in jDrotected places on the bark. 

 The eggs hatch within a few days and the little larvse, or nymphs, 

 at once commence to suck the juices from the young leaves and 



