EXPERIMENT STATION BULLETINS. 335 



INSECTS AFFECTING THE PEAR. 



AFFECTING THE TRUNK. 



Round-headed Apple-tree Borer (see Insects affecting the apple). 

 Flat-hcaded Apple-tree Borer (see Insects affecting the apple). 



AFFECTING THE BARK. 



Oyster-shell Bark-louse (see Insects affecting the apple). 

 Scurfy Bark-louse (see Insects affecting the apple). 

 San Jose Scale (see Insects affecting the peach). 

 Eccentric Scale (see Insects affecting the apple). 

 European Fruit-scale (see Insects affecting the plum). 

 Fruit Bark-beetles (see Insects affecting the peach). 



AFFECTING THE BRANCHES. 



Apple-twig or Grape-cane Borer (see Insects affecting the grape). 



AFFECTING THE FOLIAGE. 



The Pear Psylla. (Psylla pyricola.) 



Fig. 59.— Pear Psylla, adult and nymph, enlarged, from Slingerland. 



Occasionally we hear of trouble arising from the pear psylla, an European in- 

 sect, which was first noticed in Michigan in 1891. The presence of this insect 

 is usually indicated by a general loss of vitality in the tree, early in the season. 

 The young growth droops, and sometimes considerable foliage and fruit drop 

 from the tree. The leaves are seen to be smeared with honey-dew, which at- 

 tracts ants and wasps, and which supports a black, sooty fungus later in the 

 season. 



The immature insects are very small, a little more than one-sixteenth of an 

 inch in size, yellow at first but afterward becoming marked with black and 

 red. They hatch from the eggs in May and immediately commence sucking 

 the juice of the leaves. The secretion of honey-dew is so copious that the in- 

 sects soon become surrounded by small puddles of this sticky liquid, in which 

 they sit and grow. In about a month, they change to the adult, winged form 

 (Fig. 59), in which stage they are provided with wings, and with strong jumping 

 legs. "When disturbed, they jump and fly away, sometimes being so numerous as 

 to appear to fly in droves. Several broods are reared in one season. 



REMEDIES. 



Spray with weak kerosene-emulsion (Professor Slingerland recommends the 

 emulsion given in our chapter on insecticides, diluted as much as 25 times). 



