206 MANUAL OF GARDENING 



the yellow leaf -hoppers feed on th* leaves. Spray, whenever necessary, 

 with kerosene emulsion, diluted with 6 parts of water, or whale-oil or 

 any good soap, 1 lb. in 5 or 6 gal. of water ; or a tobacco extract. 



The rose-chafer is often a most pernicious pest on roses, grapes, and 

 other plants. The ungainly, long-legged, grayish beetles occur in sandy 

 regions and often swarm into vineyards and destroy the blossoms and 

 foliage. Spray thoroughly with arsenate of lead, 10 lb. in 100 gal. of 

 water. Repeat the application if necessary. (See under Rose on 

 page 395.) 



San JosS scale. — This pernicious scale is nearly circular in outline 

 and about the size of a small pin head, with a raised center. When 

 abundant, it forms a crust on the branches and causes small red 

 spots on the fruit. It multiplies with marvelous rapidity, there being 

 three or four broods annually in New York, and each mother scale may 

 give birth to several hundred young. The young are born alive, and 

 breeding continues until late autumn when all stages are killed by the 

 cold weather except the tiny half -grown black scales, many of which 

 hibernate safely. Spray thoroughly in the fall after the leaves drop, 

 or early in the spring before growth begins, with lime-sulfur wash, or 

 miscible oil 1 gal. in 10 gal. of water. When badly infested, make two 

 applications, one in the fall and another in the spring. In case of large 

 old trees, 25 per cent crude oil emulsion should be applied just as 

 the buds are swelling. Lime-sulfur is now the standard remedy. 



In nurseries, after the trees are dug, fumigate with hydrocyanic 

 acid gas, using 1 oz. of potassiimi cyanide for every 100 cu. ft. 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 pres- 

 ence of moisture renders them liable to injury. 



Tent-caterpillar. — The insect hibernates in the egg stage. The 

 eggs are glued in ring-like brownish masses around the smaller twigs, 

 where they may be easily found and destroyed. The caterpillars 

 appear in early spring, devour the tender leaves, and build unsightly 

 nests on the smaller branches. This pest is usually controlled by the 

 treatment recommended for the codlin-moth. Destroy the nests by 

 burning or by wiping out when small. Often a bad pest on apple trees. 



Violet gall-fly. — Violets grown under glass are often greatly injured 

 by a very small maggot, which causes the edges of the leaves to curl, 



