3."»4 Report of the Department of Entomology of the 



of the leaves, is especially destructive since it occurs at the time 

 when the trees should be making their best growth. Injuries at 

 this season are usually attended with more serious consequences 

 than those occurring later. If conditions are favorable for the 

 continuous breeding of the pest the damage becomes more aggra- 

 vated with each succeeding brood and as a result there is a severe 

 check to the growth of the trees. The leaves become stunted and 

 discolored, being covered with dead, brown areas as a result of the 

 extraction of the plant juices or of sun-scalding from the collection 

 of honeydew on the leaves. If the attack is of long duration the 

 leaves drop in large numbers and in some seasons trees are com- 

 pletely defoliated. Aside from direct injuries to the stems, the 

 fruit suffers from the loss of foliage, ceases to grow in size, and during 

 a prolonged outbreak much of the crop may fall prematurely. The 

 trees endeavor to put forth new growth which, under the circum- 

 stances, is usually feeble. The new leaves are generally few in 

 number and pale in color, contrasting strongly with the smutty, 

 discolored wood and dark, stained foliage which has not yet fallen. 

 Such an attack may not only check production for several years, 

 but if repeated may prove fatal. Trees that have suffered from the 

 psylla enter the winter in a weakened state and are susceptible to 

 further injuries by low temperatures. Hard winters are not infre- 

 quently attended with the death or a languishing condition of pear 

 trees following a severe outbreak of the insect. 



Another attendant of an infestation by this pest is the blackening 

 of the leaves and wood, which appear as if they had been smoked. 

 This discoloration is due to the presence of the " sooty fungus " 

 (Fumago salicina) which finds in the honeydew a congenial medium 

 for its growth. The plant itself is harmless as it grows superficially 

 and does not penetrate into the vegetable tissues. However, the 

 fungus and the honeydew together form a coating over the tree 

 which can hardly fail to affect detrimentally the normal vital action 

 of the leaves and bark. Certain ants and flies are very fond of the 

 honeydew and are often attracted by it in large numbers to infested 

 trees. 



DESCRIPTION OF INSECT AND LIFE HISTORY. 



The Psyllidse, to which this pest belongs, are closely related to 

 the plant lice and they have certain habits in common with them. 

 Both are sap-sucking insects, they have a high birth rate, and many 

 generations are produced during the year. Psyllas are sometimes 

 called jumping plant-lice on account of habit of the adult of giving 

 a quick jump when disturbed and flying to a place of safety. 



The stages in the development of this insect are the egg, larva or 

 nymph, and the adult or fly. The egg is a small body, measuring 

 about one-seventieth of an inch long, and is of an orange-yellow 

 color. It is pear-shaped with the small end drawn out into a thread 



