ATTACKING THE BRANCHES. 145 



in volume and protrudes from under the scale. Early in the 

 season they crawl out and distribute themselves over the 

 smooth bark, appearing as minute whitish specks. When 

 magnified, they are found to be of an oval form, somewhat 

 flattened, about one-hundredth of an inch long, of a dull- 

 white color, with six legs and short untennje. The young 

 lice attach themselves to the bark, which they puncture with 

 their beaks, living on the sap, and during the season mate- 

 rially increase in size. They pass the winter in a torpid state, 

 and in the spring the males enter the pupal condition, and 

 subsequently appear as minute two- winged flies, while the 

 females gradually grow to the size and form of the scales 

 referred to, and after depositing their eggs die, when their 

 dried bodies remain to serve as a shelter for their offspring. 

 This is believed to be identical with the bark louse which 

 occurs upon the pear-tree in Europe. 



Remedies. — Fortunately, these insects are of such a size that 

 they are easily seen. They should be looked for during the 

 latter part of June, at which time the females will have 

 attained their full size, and, when discovered, should be 

 promptly removed. The under side of the limbs should 

 also be well scrubbed with a brush dipped in some alkaline 

 solution. 



A small, four-winged parasite liv^es in the bodies of the 

 females, feeds upon their substance and destroys them, and 

 forms a chrysalis under the scale. When this fly matures, it 

 gnaws a round hole through the scale and escapes. 



No. 70.— The Pear-tree Psylla. 



Psylla pyri Schmidb. 



During the middle of May, when growth is rapid, the smaller 

 limbs and twigs of pear-trees are sometimes observed to droop ; 

 a close examination reveals a copious exudation of sap from 

 about the axils of the leaves, so abundant that it drops upon 

 the foliage below, and sometimes runs down the branches to 

 the ground. Flies and ants gather around in crowds to sip 



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