12 SOME INSECTS INJURIOUS TO TRUCK CROPS. 



near the bottom, causing bunches of the phxnt 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 1904, 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 destroying the last vestige of cress 

 in one of his ponds they remained on the 

 bottom " a foot deep," crawding about on 

 the mud. 



During 1906 (June 18) Mr. John H. 

 Eeed, 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- 

 FiG. 3.-The water-cress sowbug scrved principally on the roots and lower 

 (Mancasdius bmchyurun). En- leavcs, crawliug up aloug the stcm and 



larged (after Richardson). ^^^^^.^^^ ^^ ^^^- ^^^^^^^^ ^^^^^^^^ ^^ ^^^ 



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. AVhen the 

 plants were lifted the sowbugs were observed to drop from them. 



METHODS OF CONTROL. 



Three ways of controlling this species are suggested. The first 

 and most important consists in a method of growling 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 



