New Jersey 

 Agricultural Experiment Stations 



BULLETIN 328 



FEBRUARY 15, 1918 



/ 



Some Important Orchard Plant Lice 



BY 



Thomas J. Hkadlhi;, Ph.D. 



In zvinter. small {i/jO of an inch long) shining-black oTal 

 eggs on the roughened places or close to the buds of the small 

 tender twigs of the apple tree: in spring and early summer, 

 small variously colored lice congregated on the undersides of the 

 leaves causing them to curl up, die, and fall off, dwarfing the 

 fruit and sometimes ruining the crop. 



Introduction 



Four species of plant lice are usiialh- listed as commonly 

 rittacking the foliage and to some extent the fruit of the apple 

 tree. All winter in the egg stage on the smaller loranches and 

 twigs of the trees. All hatch from the eggs and develop one 

 or more generations on the tree. .\11 except one — the green 

 apple aphi.s — migrate from the apple to other plants. All return 

 to the apple either the first or second fall following and lay 

 the over-wintering eggs. The species concerned are the green 

 'ipple aphis (Aphis pomi DeG. ), the rosy apple aphis (Aphis 

 sorbi Kalt. ), the oat aphis iSiphocoryne aveme Fah. ) and the 

 clover aphis (ApJiis bakeri CoAvsen). 



In New Jersey the clover aphis has not hecn recorded. L'nlil 

 two years ago the green apple aphis was the onK s])ecics re- 

 garded as a pest. In the season of 1015 the ro^\- a])ple aphis 

 appeared in large numbers in almost all parts of the state and 



(5) 



