258 The Spraying of Plants. 



mer ; these hatch in a few days, and the maggot, after tunneling 

 for about six weeks, leaves the fruit, and enters the ground, 

 where it pupates. The mature flies appear the following 

 summer. 



Treatment. No effectual remedies are yet known. It is 

 scarcely possible that arsenical sprays will lessen the trouble ; 

 but the destruction of the young affected fruit, if well done, 

 would materially reduce the danger of injury. 



Oyster-shell Bark-louse (Mytilaspis pomorum, Bouche). De- 

 scription. The small brownish scales which are commonly seen 

 upon apple trees have been secreted by a little insect which may 

 be found underneath them during the summer. The scale, or 

 shell, protects the insect, and the latter can scarcely be reached 

 by any application made at this time of the year. But in early 

 spring the scales contain a number ot J ight-colored eggs. 

 These hatch in May, and during warm weather the young 

 insects crawl about, and in a few days attach themselves to the 

 bark. They then begin to secrete a shell which soon resembles 

 that of the parent. 



Treatment. Since the bark-louse is a sucking insect it cannot 

 be destroyed by arsenites or similar poisons. Spray affected 

 plants with some insecticide which kills by contact, such as 

 kerosene emulsion, or tobacco water. These applications should 

 be made before the young insect has attached itself to the bark. 

 Before the eggs hatch it is well to scrape badly affected parts, 

 and then to wash them thoroughly with some good insecticide, 

 those of a soapy nature being preferable. 



Tent Caterpillar (Clisiocampa Americana, Harris). Descrip- 

 tion. The moths are three-fourths of an inch long, the spread of 

 the wings being about one and three-fourths inches. The general 

 color is brown, but there is a darker band near the outer mar- 

 gin of the fore wings. In July the moths lay their eggs closely 

 in rows around the smaller twigs of trees, sometimes as many 

 as three hundred being deposited. These eggs do not hatch 

 until the following spring; then the caterpillars appear, and 

 begin to feed upon the young leaves. After a few days they 

 commence to spin their web, which soon grows to be large and un- 

 sightly. When full grown the caterpillars are about two inches 

 long ; they are somewhat hairy, and have a white streak run- 

 ning along the center of the back. The sides of the body are 



