PROCEEDINGS, 1915. 



SOME HEMIPTERA ATTACKING THE APPLE. 



By W. H. Brittain, Provincial Entomologist. 



* I ''HE following is a brief account of some of the more important 

 -*• species of the order Hemiptera attacking the apple in Nova Scotia. 

 The short popular descriptions of the insects and their work are for 

 the benefit of those not acquainted with these forms; the life histories 

 given have, for the most part, been worked out by us during the past sum- 

 mer and therefore only represent the work of one season. 



Orchard Aphids. 



Among the insect pests of crops, members of the family Aphididae 

 (aphids or plant lice) take a prominent place. All our aphids are small 

 species, none being more than one quarter of an inch long and most of 

 them much smaller. They are more or less pear shaped in form, have 

 relatively long legs and antennae and a four jointed beak of varying 

 length. The antennae have from 3 to 6 cylindrical joints. On the back 

 of the fifth abdominal segemt nt there are usually a pair of tubes called 

 cornicles, through which a clear transparent substance is secreted. 



Of the insect enemies of the apple in Nova Scotia, this family sup- 

 plies two pests of prime importance, viz. the Green Apple Aphis (Aphis 

 pomi DeG.) and the Rosy Apple Aphis (Aphis sorbi Kalt.) ; also one pest of 

 minor importance viz., the Woolly apple aphis (Eriosoma lanigera Hausm). 



In explanation of the terms used in describing the various stages of 

 aphids and their work, the following definitions are given. 



Primary Host. The plant upon which the egg is laid and upon 

 which the insect first feeds, is known as the primary host. Some species 

 spend their entire lives on one plant, but others migrate to other plants 

 and there spend a part of their life history. 



Secondary Host. The plant to which the aphids migrate and spend 

 a portion of their life history, is known as the secondary or alternate host. 



The Stem Mother. The form which hatches from the egg in the 

 spring, and is the mother of all succeeding generations, is known as the 

 stem mother. The stem mothers are all females, which produce living 

 young without being fertilized. Because the young are born alive the fe- 

 males are said to be viviparous. The production of young without the 

 intervention of males is called parthenogenesis. 



The Spring Migrant. In the second or third generation of certain 

 species of aphids, winged forms appear that leave their primary host and 

 fly to some other plant, where they settle down and produce young. The 

 term pupa is applied to the stage preceding the winged form. In this 

 stage the wing pads are distinctly visible. 



Fall Migrant. One of the fall brood of wings forms that fly back 

 to the primary host. 



