82 FARM FRIENDS AND FARM FOES 



JUMPING PLANT LICE 



The Jumping Plant Lice (Psyllidae) are few in number of 

 species, and with the exception of the Pear Psylla are of 

 comparatively little economic importance. This Pear Psylla, 

 however, often becomes a very serious pest, attacking pear 

 trees in overwhelming numbers, and sucking out the sap 

 to such an extent as to cause great injury. The adult 

 insect, which is only about the size of an ordinary plant 

 louse, passes the winter on the bark of pear trees, commonly 

 more or less concealed within crevices. They deposit their 

 eggs very early in spring, especially about the buds or 

 upon the unfolding leaves. In two weeks or so, the eggs 

 hatch into tiny larvae which attack the petioles of the 

 leaves as well as their general surface. In about a month 

 each larva reaches maturity, having molted five times 

 during the process. There are several broods each year, 

 the number doubtless varying with the locality. 



Like the aphides, these insects secrete a large amount 

 of the so-called honey dew, which consists chiefly of the 

 sap of the plant that has passed through the bodies of the 

 insects. Where a pear tree is badly infested, this honey 

 dew covers the leaves, often collecting in large drops, 

 which are believed to act sometimes as lenses in condensing 

 the sun's rays so as to burn the foliage beneath. Upon 

 this honey dew, there also develops a black fungus that 

 soon gives the leaves and fruit of the infested tree a strange 

 blackened appearance. 



SCALE INSECTS OR COCCIDS 



The strange Scale Insects or Coccids (Coccidae)form one 

 of the most important groups of the Homoptera. Many 

 of these are commonly known as Bark Lice, because they 



