660 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



trees anil may be found establishing their colonies upon various 

 succulent vegetables," such as cabbage, turnip, rape, tomato, 

 celery, and a long list of vegetables and flowers grown in green- 

 houses, where this species is a pest the year round. The list of food- 

 plants is a long one, the largest of any species known to him, accord- 

 ing to Professor C. P. Gillette, but it is a common and sometimes 

 troublesome pest of cabbage (See p. 374) and celery and one of 

 the most abundant of the various sorts of " green fly " of the 

 greenhouse. The winged females which migrate from the peach 

 are about one-twelfth inch long, with a wing expanse of one-third 

 inch. They are a yellowish-green color with head, antennae, 

 thoracic lobes, honey-tubes, a large spot on the centre of the 

 abdomen, and small lateral spots in front of the honey-tubes are 

 blackish. The honey-tubes, or cornicles, are cylindrical, while 

 those of the winged females in summer and fall are decidedly 

 swollen toward the tip and constricted at the base, giving them 

 a club shape, on account of which they were placed in the genus 

 Rhopalosiphum. Otherwise the winged females of summer and 

 fall are very similar, except that they are more yellowish and the 

 markings and cornicles are lighter. The wingless females during 

 the summer are pale yellowish and lack the longitudinal green 

 stripes on the abdomen. According to Taylor's observations the 

 spring generations on peach become full grown in about two 

 weeks and an individual aphid lives about a month. As repro- 

 duction is probably more rapid in summer, the aphides may soon 

 become very abundant. In the fall winged females return to the 

 peach and winter host-plants, and give birth to young which 

 develop into wingless females which lay the winter eggs. The 

 true males are winged and migrate from the summer food-plants. . 

 Control. The trees affected should be sprayed about a week 

 before the buds open with 5 to 7 per cent kerosene emulsion, 

 tobacco extract, or whale-oil soap, 1 pound to 5 gallons, or miscible 

 oil diluted 20 times. If the trees are sprayed with lime-sulfur 

 for the twig-borer just before blossoming, it should kill most of 

 the aphides. The same remedies may be used on the foliage of 

 affected plants as necessary. 



