THE WATER-CRESS SOWBUG. 13 
& Son, who are practical cress growers and have had several years' 
experience with the pest : 
A METHOD OF GROWING WATER CRESS TO DISPOSE OF THE SOWBUG. 
The damage done by the sowbug to water cress has made it our greatest 
enemy in cress growing, and only after fighting it for four years have we suc- 
ceeded in finding a way to keep down its numbers so as to be sure of a crop. 
As cress is ordinarily grown — in lakes or streams of spring water anywhere 
from 6 inches to 3 feet in depth — it seems impracticable to apply any insecti- 
cide. At first we tried to catch the bugs with wire-netting traps placed where 
the whole stream of water had to pass through them, but the bugs remained 
among the cress, and we caught only about 20 per cent. 
Later, in using copper sulphate to kill moss in the cress, we found that it 
also killed the sowbngs, snails, etc., when applied freely. Further experiments, 
however, proved that bluestone could not be applied in deep running water any 
better than the insecticides previously tried, and when applied in shallow or 
still water it injured the cress. 
The method we are employing at present to fight the sowbug is largely a 
matter of arrangement of cress beds (see fig. 4), and can be used only where 
the bottoms of the beds can be graded and drained or where level land adjoins 
Fig. 4. — Cross section of cress pond showing arrangement for avoiding damage by the 
water-cress sowbug. 
the source of the water supply. We dug long trenches in level land, making 
them 1G feet wide and about 15 inches" deep. Lengthwise they were graded to 
give a fall of 3 inches in 100 feet, and crosswise to make the center of the 
trench several inches deeper than the sides. In the center and running the full 
length of the trench a trough made of three 10-inch boards was sunk below the 
bottom of the trench in such a way that all of the water might be drained out 
of the trench through it. Then, with the upper and lower ends of the trench 
and trough arranged to be opened or closed, the trench could be filled or emptied 
at will and the flow of water regulated up to 8 inches in depth over the cress. 
Of course fertile soil was put in the trenches aiid the cress could be planted 
either before or after the water was turned in. 
With cress beds arranged as above, manipulation to dispose of the sowbngs 
is simple. By cutting off the water supply and allowing the water to pass out 
at the lower end of the trench, the sowbngs will collect in the trough, following 
the receding water, as they can live only in water. No little puddles should 
remain among the cress, as the bugs will collect in them Instead ol' in the trough. 
It will be found necessary, also, to use boards to walk on in gathering the cress, 
as prints of one's boots in the beds would make holes for the hugs to shelter in. 
The bugs do not move until nearly all of the water is drawn out o( the trench. 
Thus they are collected in a small amount of water in the trough ami can then 
be readily killed with a liberal amount of bluestone, either solid or in solution. 
