The Pear Psylla. 115 



begia spraying; about May 15 is usually the time in this State. 

 Where they are numerous, a second or third spraying will be nec- 

 essary. The emulsion tmist he applied liberally and thoroughly ; 

 it will not injure the tree in the least. It is much more difficult to 

 fight the insect later in the summer, when the tree is in full foliage 

 and many of the nymphs are covered with honey-dew. Watch for 

 their appearance on the unfolding leaves in the spring and act 

 promptly. Spray two or three times in a week if necessary ; make 

 every effort to prevent the development of a second brood. 



The adults. — In Bulletin 44 we suggested that a thorough wash- 

 ing of the trunks and larger branches of the trees in winter with 

 kerosene emulsion (at least five per cent, kerosene), or a strong 

 soap solution, would destroy many of the adults in hibernation 

 in the crevices of the bark. It is reported that a whale-oil soap 

 solution has been thus used very effectively in New Jersey. We 

 believe it is a practical method, and should be practiced in 

 infested orchards. 



We once saw hundreds of the hibernating adults congregated 

 on the smooth trunks of a large block of young standard pear 

 trees. There were twenty-five or more on each tree, and all of 

 them on the same sides of the trees. It was a short job with a 

 rag or mitten to grasp the tree at the base, draw the hand up the 

 trunk and thus crush the psyllas. 



Is it practicable to fight the adults in summer ? They are then 

 often very numerous but are very shy and active, and fly from the 

 tree the moment the spray strikes it. It would thus seem that 

 " spraying has practically no value against the adults during their 

 active summer existence " (Mr. Marlatt). However, several of our 



now be readily diluted with cold water, preferably with rain water. Or the 

 whole mass may be allowed to eool when it has a semi-solid form, not un- 

 like loppered milk. This stock if covered and placed in a cool dark place 

 will keep for a long time. In making a dilution from this cold stock 

 emulsion, it is necessary to measure out the amount of the emulsion re- 

 quired and first dissolve it in three of four parts of boiling water; if cold 

 water be used a large quantity of a white flocculent mass rises to the sur- 

 face and does not dissolve. After the stock emulsion is dissolved, cold 

 water may be added in the required quantities. If all the utensils are 

 clean, and the directions followed closely, no free oil will rise to the sur- 

 face of the dilution. 



