566 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



stroyed than when under the bud scales. In spring spray just 

 as the buds begin to break and show the tips of the young leaves; 

 spraying later than this will injure the foliage, and earlier spraying 

 is not as effective. By using lime-sulfur in the spring, the usual 

 treatment with Bordeaux mixture for diseases at that time is 

 rendered unnecessary. Where infestation is serious both fall and 

 spring sprayings should be given; otherwise the fall spraying is the 

 better. The buds and new growth should be thoroughly drenched, 

 while the rough bark of the trunk and old limbs may be neglected 

 as far as the mites are concerned. Where pear trees are but 

 slightly infested, the spread of the pest may often be prevented 

 by simply pruning out and burning the infested twigs upon the 

 first appearance of injury. 



The Pear Psylla * 



Where the pear psylla is abundant, pear growers have come 

 to fear it next to the San Jose scale, and until recently owners 



FIG. 502. The pear psylla (Psylla pyricola Foerst): adult, full-grown nymph 

 and egg all greatly enlarged in different proportions. (After Slinger- 

 land.) 



in eastern New York became so discouraged in their attempt to 

 control it that orchards were cut down. It is an old European 

 pest and was first noted in Connecticut in 1832, since when it has 

 spread southward to Maryland and Virginia and westward to 

 Michigan and Illinois, in which States it has done considerable 

 injury. The psyllas are nearly related to the plant-lice and are 



* Psylla pyricola Foerst. Family Psyllidce. See M. V. Slingerland, 

 Bulletins 44 and 108, Cornell Univ. Agr. Exp. Sta.; C. L. Marlatt, Circular 

 7, Div. Ent., U. S. Dept. Agr. 



