CARROT AND PARSNIP FLY. 
38 
and if a sprinkling (about enough to give the appearance of hoar¬ 
frost) of gas-lime, in absolutely fresh and caustic state, was thrown on 
the surface, it could not fail to kill those of the pests that it touched. 
Of course, as before mentioned (see p. 30), some weeks must be allowed 
to elapse before land so treated is safe for cropping or sowing. Where 
ground has been rough-dug at the beginning of winter, sprinkled with 
gas-lime, and the gas-lime then pointed in about four inches deep, 
this plan has answered; the Carrots have been found to escape 
** rust,” whilst those not so treated were destroyed. 
For prevention of attack generally, what is needed is a well- 
prepared soil which will push on good growth of the plant, and also 
not be liable to crack, and also such management of ground and 
plants at thinning-time as will not allow the Carrot Fly to get down 
to lay its eggs by the roots. This point is the important matter in 
prevention of the Carrot-grub attack , commonly known as “ rust." If the 
fly cannot get to the roots to lay her eggs, obviously there will be no 
maggots to harm them, and the reason why Carrots which have done 
well up to thinning-time often fail afterwards, is because the ground is 
thrown open in the operation. 
To get over this point, treatment which will close up the soil as 
much as possible after thinning is needed, and waterings, with an 
addition of something which will be deterrent to the fly, and also will 
push on vigorous growth (as guano or soot and water), are especially 
useful. I have myself stopped attack (which only commenced after 
thinning) by watering with a very dilute form of a preparation called 
Soluble Phenyle. The injury was stopped, and the plants thrown 
into vigorous growth. Paraffin has been found very successful in 
checking attack. If applied in fluid-state, care must be taken that it 
is not strong enough to burn the plants, and probably a little in a 
solution of soft-soap would be the safest form : 3 lbs. of soft-soap and 
one pint of paraffin in 25 gallons of water, raised to boiling-point in 
mixing, would perhaps be as good a proportion as any ; but no rule 
can be given—trial must be made. Paraffin dressings would be of 
use, mixed with sand, dry earth, ashes, or other dry material. A 
proportion of a quart of paraffin to a bushel of the dry material has 
been found not to injure perfectly tender young shoots of other plants. 
But the great point is to keep the Carrots protected from possibility 
of fly getting at them. In the heavy thunderstorm of June 26th, in 
1888, a rainfall at the rate of nearly two inches an hour fell during 
about three-quarters of an hour at St. Albans, sweeping all that was 
movable before it in gardens or road, down the steep slope of Holywell 
Hill. In my own garden a bed of Carrots, upwards of 63 ft. long and 
about 4 ft. wide, lay across the slope, with plots of garden ground 
above, and a thick border of box varying from 3 to 4 ins. below it. 
