S.")G Report of the Department of Entomology of the 



a much longer period. During the first week in May or about the 

 time the cluster buds break apart the eggs begin to hatch and the 

 young nymphs at once commence to suck the juices from the suc- 

 culent twigs and leaves. The largest number of nymphs will usually 

 be present on the trees about the time blossoms drop. A favorite 

 place for the nymphs at this time is in the axils of the leaves and at 

 the bases of the fruit stems. Within two or three days after hatch- 

 ing the nymphs cover themselves with honeydew which may even- 

 tually become so abundant as to disfigure the foliage and fruit. 

 The amount of injury done by the insect varies to a large degree 

 with the number of the nymphs. When numerous they take so 

 much nourishment from the trees that the new growth, as previously 

 described, is seriously checked and the trees assume a stunted, 

 unhealthy appearance. 



Successive generations of nymphs occur during the summer, 

 approximately one month apart. The period of incubation of the 

 eggs of the summer broods is shorter than with those deposited by 

 the winter hold-over flies and averages about ten days. 



With the approach of cold weather in the fall all of the insects are 

 in the adult stage and these seek the shelter of the bark of the trunks 

 and large limbs for protection for the winter. 



NATURAL ENEMIES. 



The pear psylla has several insect enemies which exert a marked 

 regulatory and repressive action upon its multiplication. Most 

 common and efficient enemies are a lace-winged fly and various 

 lady-bird beetles. The psylla is also subject to the attacks of a 

 parasite which develops within the bodies of the host. It seems to 

 be a widely distributed and a very common attendant of the pest 

 and destroys many of the nymphs. Parasitized nymphs of the last 

 instar are bloated in appearance, and during some seasons they may 

 be found in considerable numbers concealed in the rough bark of 

 the trunk and larger branches of the tree. Useful as are the parasites 

 they only limit the extent of damage and do not prevent the psyllas 

 from developing in destructive numbers. If perfect immunity is 

 desired the work of these natural auxiliaries should be supplemented 

 by active measures on the part of the grower. 



VULNERABLE STAGES OF PSYLLA AND SPRAYING DIRECTIONS. 



Of the several broods of the psylla the hibernating or winter flies 

 and the first brood of eggs and newly-hatched nymphs are most 

 susceptible to spraying. Recent experiments conducted on a large 

 scale have demonstrated the practicability of destroying this pest 

 in these stages so that, as the season advances, sufficient numbers 

 do not develop to cause important injuries. Directions for spraying 

 are as follows: 



