24 



THE PEAR-TREE PSYLLA. 



My orchard was seriously injured the past season by the pear-tree 

 psylia, {Psylla pyri,) a minute winged scale like insect, that injures 

 the trees by sucking their juices and is proving a serious pest where- 

 ever it gets a foot-hold. Its presence is first made known by what is 

 called by some, honey dew, a sticky substance exuded by the insects 

 and often causing the decay of the leaf, or possibly favoring the 

 attack of the leaf blight fungus, which causes the leaves to fall. 

 This insect has, in some instances, caused the death of large orchards 

 and would iu all cases, did not its natural enemies, wasps and hornet 

 or untoward seasons prevent. We never can predict with certainty 

 the outcome of one season from the results of tne last. 



The best agent known for this class of ihsects is kerosene, which, 

 for this purpose, must be made into an emulsion and if properly 

 made and applied, it does no harm to the foliage. 



My formula for this emulsion is ^ lb. of common yellovr or rosin 

 soap dissolved in a gallon of boiling water, to which is added two 

 gallons of kerosene and the whole churned together by means of the 

 Hydrosprayer or other syringe for three to five minutes, producing 

 an emulsion, separating the kerosene into minute globules, the whole 

 looking somewhat like whipped cream. One part of this emulsion 

 added to nine or more parts of water is sprayed upon the foliage and 

 kills the insect at once, without harm to the foliage. Tliis is best 

 applied in a dry atmosphe'-e. 



I applied this preparation to about four acres of pears, June 10th 

 to 12th and again July 17th to 22d. The psylia appeared first June 

 8th, in considerable numbers, in the vs^inged form, and honey dew 

 followed in two or three days afterward. It has been supposed to 

 live over winter in the egg like other forms of aphides, but I am' very 

 confident that in my case the perfect insect appeared first. Soon 

 after the second spraying the honey dew mostly disappaared and the 

 partially blighted leaves gradually resumed in some degree their 

 natural color. Eggs and larvae were found in considerai)le numbers 

 on the leaves, but they did not thrive and gradually disappeared 

 mostly without maturing. What the outcome is to be I can only 

 guess. If the eggs are laid on the twigs in autumn, then kerosene 

 emulsion, or perhaps a potash solution might be depended on to 

 destroy them. If, as I am confident, they hibernate in the winged 

 state, I should depend upon burning the stubble in the spring, and 

 the use of kerosene emulsion whenever they showed tliemselves in 

 numbers." 



