266 INSECTS AFFECTING VEGETATION 



the plants. It is therefore very important that the directions for 

 treatment be followed carefully. The best proportion of cyanide, 

 sulphuric acid, and water seems to be 



1 ounce cyanide of potassium, 



2 ounces commercial sulphuric acid, 

 4 ounces water. 



The water should be poured into the receiving vessel first ; then 

 the acid should be added; then the cyanide as directed more fully 

 below. Pour the acid into the water; never pour the water into the 

 acid. In our experiments we used 1 ounce of cyanide to 400 cubic 

 feet of space, and left the house closed but nine minutes. Do not ex- 

 pose the plants to the gas longer than this. (Bui. 100 New Hamp. 

 Exp. Sta.) 



The Greenhouse Leaf-Tyer. The insect may include in its 

 menu almost any soft-leaved greenhouse plant. In the horticultural 

 greenhouses here, it has been especially troublesome on lettuce, sweet 

 peas, clover, parsley, cinerarias, chrysanthemums, geraniums, straw- 

 berries and cucumbers. The caterpillars usually w r ork on the under- 

 sides of the leaves eating over irregular areas through to, but leaving 

 the upper skin of the leaf. Similar work is done on other thick- 

 leaved plants, like chrysanthemums and geraniums. The thin leaves 

 of lettuce and parsley were eaten entire, while those of sweet peas and 

 clover were skeletonized. Often the caterpillars exhibit their rolling 

 or tying habits and two or three small leaves may be loosely tied 

 together with silken threads, or on larger leaves silken bands are 

 stretched across from one large vein to another, often resulting in par- 

 tially folding or kinking the leaf; the caterpillar works under the 

 silken bands in the fold. But many times there is no tying or rolling 

 of the leaves, the caterpillar feeding openly on the underside under a 

 few silken strands. 



The adult insect is a small rusty-brown moth with somewhat 

 obscure blackish markings on its front wings. In greenhouses the 

 moths may be found resting during the day in angles made by the 

 framework, and also out of sight on the plants. They fly readily 

 when disturbed, but soon alight and rapidly run to the underside of 

 the object on which they alight; when cold, they are less active, and 

 thus more easily captured. They are attracted by lights. 



The much flattened, elliptical, translucent eggs of the insect are 

 closely attached to the undersides of the leaves in clusters of from 

 eight to twelve, often two to four of which may overlap. The egg 

 shell is finely reticulated, and is apparently not easily penetrated by 

 liquids as caterpillars were reared from eggs which had been soaked 

 in water for two days. Observations indicate that the egg-stage lasts 

 about twelve days. 



The full-grown caterpillar or larva is about three-fourths of an 

 inch long, and of a general translucent greenish-white color; its head 

 is of a dark straw color with darker mottlings, and there is a small, 

 conspicuous black spot in the center of each half of the prothoracic 

 shield. A narrow dark green stripe extenols medially along the back, 

 bordered on each side by a much wider, light greenish-white stripe; 



