The Control of Insi-xt Pests and Plant Diseases. 



593 



This plant-louse is harder to kill than the green aphis, but may 



be controlled by the same methods. 



Syringe ofiF the plants with clear water two or three times a 



week, taking care not to drench the beds. 



"Violets grown under glass are often greatly injured by a very 



small maggot, which causes the edges of the leaves to curl, 



turn yellowish and die. The adult is a very minute fly resem- 

 bling a mosquito. Pick off and destroy infested leaves as soon as discovered. 

 Fumigation is not advised for this insect or for red spider. 



Black aphis. 

 Red spider. 



Violet gall-fly. 



NURSERY STOCK. 



Spray thoroughly or dip the tips in kerosene emulsion, diluted 

 Plant-lice. with 6 parts of water, or whale-oil soap, i lb. in 5 gals, of water; 



or one of the tobacco extracts may be used. 



After the trees are dug, fumigate with hydrocyanic acid gas, 

 San Jos^ scale, using i ounce of potassium cyanide for every 100 cubic feet of 



space. Continue the fumigation from one-half to three-quarters 

 of an hour. Do not fumigate the trees when they are wet, since the presence of 

 moisture renders them liable to injury. 



ONION. 



Onion tops frequently turn white and die as the result of the 



Onion thrips. feeding punctures caused by these minute yellowish insects. 



The injury is known as "white blast," Spray thoroughly with 



kerosene emulsion diluted with 6 parts water, or whale-oil soap, i lb. in 4 gals, of 



water, or with one of the 



tobacco extracts. 



Onion maggot. For treatment see cabbage 



ROOT-MAGGOT, page 476. 



PEACH AND APRICOT. 



The adult is a clear wing 

 Peach borer, moth. The larva burrows 



just under the bark near 

 or beneath the surface of the ground; its 

 presence is indicated by a gummy mass at the 

 base of the tree (Fig. 201 ). Dig out the borers 

 in June and mound up the trees. At the same 

 time apply gas-tar or coal-tar to the trunk from 

 the roots up to a foot or more above the surface 

 of the ground. Cornell Bulletins 176 and 192. 

 Plum CUrculio. See under plum. 

 San ]os6 scale. See under APPLE. 



PEAR. 



Pear psylla. 



These minute, yellowish, 

 flat-bodied, sucking insects 

 are often found working in 



Fiii. 201. — Fcach borer. 



