42 _ NEW YORK STATE MUSEUM 



making possible the production of many generations during a 

 season. Messrs Houser, Guiton and Lowry^ have estimated that 

 the total progeny and offspr'ng of on for a per'od of two weeks may 

 amount to 76 aphids. They found on one small potato plant having 

 only seven leaves 1237 aphids and on a large spreading plant with 

 twelve stalks 34,688 plant lice and another large one had 25,750 

 aphids. The rate of reproduction is such that it would require 

 only two weeks for 456 producing females to colonize the most 

 seriously infested of these plants. With these figures in mind it 

 is not surprising that an aphid outbreak may develop rapidly and 

 become extremely destructive almost before the presence of the 

 pests is suspected. 



This aphid breeds freely upon potato, tomato, egg plant, pepper 

 and sunfower and may be found commonly, though not in large 

 numbers, upon such well-known plants as jimson weeds, ragweed, 

 lamb's quarters, sweet potato, canna, holl3^hock and matrimony 

 vine. It also occurs, though less commonly, upon a number of 

 other plants so that it is comparatively easy for this aphid to 

 ma'ntam itself in any locality where climatic conditions are suitable. 



Characteristics of outbreak. The plant h'ce attack the tender 

 young leaves, causnig the edges to turn downward and after a 

 short time the foliage shrivels and we have a characteristic dying 

 condition. This progresses from the top downward and in very 

 seriously infested fields all the foliage may speedily succumb, part 

 of th's being very likely due to plant diseases as well as to insect 

 injury. 



The tomato is also very h'able to infestation, the aphids first 

 work-ng on the under side of the leaves, causing them to curl, and 

 also becoming very abundant upon the tender terminal portion of 

 the stalk and the blossom stems. A serious infestation results in 

 the bloom dropping without the setting of fruit, and as this occurs 

 upon the earlier blossoms the loss is frequently very considerable. 

 Fgg plants and peppers are also severely affected by this pest, the 

 aphids working as in the case of the tomato, on the under side of 

 the leaves and the greatest injury resulting, as in the case of the 

 tomato, from the attack upon the blossom and the blossom stem. 



Natural enemies. The potato aphid, like other plant lice, is 

 very subject to attack by var"ous natural enemies, especially minute 

 four-winged parasites and the black spiny grubs and adults of the 

 lady beetles. The presence of parasites in an infested field is easily 



1 Ohio Agricultural Experiment Station Bulletin 317, 1917. 



