INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 67 



freely. The nymphs are also characterized by having large and 

 conspicuous wing pads. Like the plant lice they feed upon the 

 tender foliage and bark of various plants. 



THE PEAR PSYLLA 



Psylla pyricola Forster 38 

 (Psylla pyri Curtis) 



Description. — There are two distinct forms of this species, a sum- 

 mer and winter. The adults of the summer form are light orange 

 to reddish in color with darker markings. The antennae are slender 

 and one and one-half times as long as the width of the head. The 

 legs are slender with or without basal spurs on the hind tibiae. The 

 wings are transparent. The length to the tips of folded wings of 

 the female is 1-9 inch and less for the male. The adults of the 

 winter form are larger and darker in color, varying from dark 

 reddish-brown to black. The length to tips of folded wings of the 

 female is 1-6 inch and 1-7 inch for the male. The eggs are light 

 yellow, elliptical with short pedicel at the large end for attachment 

 and a slender projection at the small upper end. 



Life History. — The eggs are deposited singly in rows of from five 

 to ten in cracks or crevices in the bark or at the bases of the terminal 

 buds of the previous year's growth. They are laid in April and 

 May and hatch in from one to four weeks after deposition. The 

 first young are light yellow with red eyes and three-jointed antennae. 

 When full-grown the nymphs are light yellowish brown or amber 

 with dark wing pads and with long marginal body spines. The 

 adult stage is reached within about a month after the eggs are laid. 

 The last brood in the fall hibernates in the adult stage in cracks 

 in the bark, under the bark, in rubbish, etc., and begins egg-laying in the 

 early spring. There are four broods a year. 



Nature of Work. — Due to the large numbers which may occur on 

 a tree at one time, serious damage is often done by this insect. The 

 leaves are curled, turn yellow and may drop, and if the attacks 

 continue, the trees may be completely defoliated. 



Distribution. — This insect was recorded as occurring in California 

 as early as 1883 by Matthew Cooke 38 but no further mention of it is 

 found in later literature. If it occurs in the State its distribution 

 is very limited to have evaded detection for so long. Crawford in 

 his work on "The Jumping Plant Lice of the World," page 145, doubts 

 its existence in the State. 39 



Food Plants.— The foliage of the pear is the only reported host 

 in America, but in Europe the apple is also sometimes attacked. 



Control.— The application of a strong winter spray of oil emulsion 

 or miscible oil will kill many of the hibernating adults. The young 

 and nymphs are readily destroyed by these sprays if there is added 

 f pint of tobacco extract (40 per cent nicotine sulphate) to 100 gallons. 

 A spray composed of f pint of 40 per cent nicotine sulphate, 5 pounds 



:JS Inj. Ins. Orchard, Vineyard, etc., p. 117, 18S3. 

 '"Crawford, D. L., Bui. 85, U. S. Nat. Mus. pp. 144-146, 1914. 



