154 INSECTS AFFECTING VEGETATION 



with carbon bisulphide, one ounce to 100 Ibs. of roots, placed in pans 

 on top of the pile, provided that they are in fairly air-tight bins. 

 They should be left for 48 hours and then exposed to the air in 

 order to get rid of the fumes, which are very inflammable ; no light 

 or fire should be anywhere near when this substance is being em- 

 ployed. 



CELERY. 



Celery, as a rule, is not much affected by injurious insects; 

 those that do attack it are the same as the enemies of carrots and 

 parsnips, to which reference is elsewhere made. The handsome 

 caterpillars of the Black Swallow-tail Butterfly may often be found 

 eating the foliage, but they are never very numerous and can easily 

 be controlled by handpicking. A small caterpillar called the Celery 

 Leaf-Tyer is sometimes abundant and injurious; it feeds for the 

 most part at night; when young it eats small holes in the leaves 

 which are hardly noticeable, but as it grows larger it becomes more 

 voracious and consumes a considerable amount of foliage. When 

 fully grown they roll up a leaf and tie its edges together with silk, 

 forming thus a convenient case in which to pass the chrysalis stage. 

 The moth is about three-fourths of an inch in expanse of wings, pale 

 brown in color, with a reddish suffusion ; the wings are marked with 

 irregular cross lines of black and some circular spots. There are at 

 least two broods in the year. The insect is sometimes known as the 

 Greenhouse Leaf-tyer from its attacking a variety of hot-house 

 plants ; out-of-doors it by no means confines itself to celery, but may 

 be found on a great variety of vegetables. As soon as the cater- 

 pillars are noticed the plants attacked should be sprayed with Paris 

 green, applied to the under side of the leaves. In the greenhouse 

 any infested leaves should be cut off and destroyed. 



One of the most serious enemies of celery is the Rust-fly de- 

 scribed among the insects affecting carrots. The maggots attack the 

 thick part of the roots of young celery plants and prevent their 

 proper growth; they also produce the characteristic rusty blotches 

 on the stems and spoil them for table use. 



Celery Aphis. Occasionally celery is infested by one of the 

 plant-lice or green-flies. The writer has never seen any serious in- 

 jury by these insects, but in case they become troublesome, kerosene- 

 emulsion should prove effective as should also tobacco water. 



Little Negro-Bug. This insect ordinarily seems to prefer 

 weeds to celery, but on occasion, it has been known to overspread a 

 celery field in late July, collecting in little clusters on the leaves, 

 and playing sad havoc with the commercial fields. The outer leaves 

 of the stalk suffer first, but later the inner, feathery ones that go to 

 make the market head. 



The cause of all this trouble is a small, shining black bug, very 

 convex and quite broad comparatively, the length being a little less 

 than one-eighth of an inch. The insect is said to rear only one gen- 

 eration each year. It is known to work on strawberry, raspberry, 

 grape, wheat, some grasses, and a number of weeds, including red- 

 root and ground-nut, beggar-tick, plantain, rag-weed and smart weed. 



