The Jumping Plant-Lice or Flea-Lice 



Life History of the Pear-Tree Psylla 



(Psylla pyricola.) 



This insect is the commonest and the most destructive flea 

 louse in the United States. It is common throughout the north- 



Fig. 154. Pear-tree Psylla: adult female natural size indicated 

 by side line. (After Marlatt.) 



eastern United States and from Maryland on the south to 

 Michigan on the west. It was originally a European species 

 and is supposed to have been imported into this country about 

 1832, making its first appearance in Connecticut. The egg is 

 orange yellow in color and very minute. It is attached to 

 the leaf by a short arm and has a long hair-like stalk pro- 

 jecting from its end. The newly hatched larva is somewhat 

 larger than the egg and yellow in color with crimson eyes. 

 It passes through several molts and when nearing the nymphal 

 condition, which corresponds to the pupa stage in insects which 

 have complete metamorphoses, it is readily distinguished by 



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