12 
SOME INSECTS INJURIOUS TO TRUCK CROPS. 
near the bottom, causing bunches of the plant to float. In portions 
of streams where these sowbugs have been found most abundantly 
they are frequently seen crawling in a thick mass at the bottom. 
They feed, so far as known, exclusively on cress, not being reported 
as attacking any other form of vegetation. 
REPORTS OF INJURIOUS OCCURRENCES. 
This sowbug has been observed as a pest since 1902. Our first 
report of its pernicious habits was made in 1901, when we received 
specimens through Mr. J. W. Bryan, Anacostia, D. C, from Hall- 
town, W. Va., where it was very injurious to water cress. 
In March, 1905, Mr. Powell Arnette reported injury at Gaylord, 
Va., to cress grown in spring water. The 
sowbugs were always found in the water 
and did not attack cress above the surface. 
After destro}dng the last vestige of cress 
in one of his ponds they remained on the 
bottom " a foot deep,'' crawling about on 
the mud. 
During 1906 (June 18) Mr. John H. 
Keed, Carlisle, Pa., wrote in regard to this 
species and its destructive work on water 
cress in his locality. Specimens were re- 
ceived August 11. The sowbug was ob- 
served principally on the roots and lower 
leaves, crawling up along the stem and 
cutting off the leaves. August 10 Mr. 
George C. Jordan, Washington, D. C., sent specimens from Basic 
City, Va., stating that this " water bug " was devouring his cress 
beds, and, since a million or more were colonized on the plants, there 
would be no crop at the rate they were reproducing. When the 
plants were lifted the sowbugs were observed to drop from them. 
Fig. 3. — The water-cress sowbug 
(Mancasellus brachyurus). En- 
larged (after Richardson) . 
METHODS OF CONTROL. 
Three ways of controlling this species are suggested. The first 
and most important consists in a method of growing the water cress 
so as to eliminate injuries by the sowbug. The second falls under 
the head of direct remedies, and none of these has as yet given sat- 
isfactory results. The third consists in the use of fish or fowls as 
destroyers. This last means of eradicating the pest has not yet had 
a fair trial. 
The following description of a successful method of disposing of 
the cress sowbug has been placed at our disposal by Messrs. B. Bryan 
