384 



Ohservcttions on the Timiip Saw-Fly. 



dicular, or even overhanging at tlie top, if possible : thus a trap 

 is laid, and the bottom of the trench will soon be entirely covered 

 vAih. them. It is likewise a very sensible precaution, when there 

 are signs of the caterpillar in one field, to cut such a trench across 

 a gateway connecting it with another enclosure where there are no 

 symptoms of its presence. If water rise in the trench, so much 

 the better ; if not, the bottom may be filled with straw, and set 

 on fire when the caterpillars have accumulated in sufficient num- 

 bers, which is a very speedy and excellent mode of destroying 

 them. 



Hand-picking and ducks are, however, most to be relied on : 

 it is true that the former is tedious, if not expensive, where the 

 caterpillars are so numerous that as many as sixteen score have 

 been counted on one large plant ; but in such cases they should 

 be brushed or whipped off into fruit-baskets or sieves ; otherwise 

 pint or smaller pots are well adapted for collecting them, which 

 can be emptied into large covered vessels at the head of the field, 

 containing some salt and water, or lime-water, to prevent the 

 caterpillars from crawling out. Mr. Sells states that a boy ten 

 years old gathered the caterpillars in a field suffering in a slight 

 ' degree, at the rate of 1 80 in an hour : eight hours per diem would 

 give nearly 1 500, or 9000 a week ; so that ten or twelve children, 

 from six to ten years old, would collect 90,000 or 100,000 in a 

 week, where they are not abundant : in such a case, 6c2. a pint, 

 and 2s a-day to the superintendent, would probably answer the 

 purpose.* 



Mr. Manning says pigs will destroy the larvae to a very great 

 extent, and without injuring the crop in the slightest degree but 

 that 1 60 young ducks soon put a stop to the black caterpillars. 

 Ducks, having been tried with universal success, are decidedly the 

 favourites : they are also useful to eat slugs and other small 

 animals destructive to field-crops and vegetables. Poultry are 

 said to be equally beneficial, with the exception of turkeys, which 

 will not touch the negro caterpillars. Fowls are naturally fond 

 of worms and caterpillars, so much so that hens' eggs, when they 

 feed much on meadows and mountains, without corn-food, are not 

 well flavoured. It is therefore not difficult to induce them to 

 make the most of their time, when they are invited to such a luxu- 

 rious banquet. Indeed it is supposed to be most judicious to turn 

 in 'poultry where the caterpillars do not abound, as they will 

 search them out, and leave the turnips uninjured ; whereas the 

 ducks, under such circumstances, would attack the turnip-tops, 

 and thus the remedy might prove as bad as the malady. 



Hundreds of ducks were turned into a field in Kent, which 



* Trans, of Ent. Soc, vol. ii. p. Ixxviii. 



