12 



SOME INSECTS INJURIOUS TO TRUCK CROPS. 



near the bottom, causing bunches of the phint to float. In portions 

 of streams AA'here 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 1002. Our first 

 report of its pernicious habits was made in 190-1, when we received 

 specimens through Mr. J. ^V. 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. 

 .Vfter destroying the last vestige of cress 

 in one of his ponds they remained on the 

 bottom '' a foot deep," crawling about on 

 the mud. 



During 1900 (June 18) Mr. John H. 

 Reed, Carlisle, Pa., wrote in regard to this 

 species and its destructive Avork on w^ater 

 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 ofi' the leaves. August 10 Mr. 

 (xeorge C. Jordan. Washington. D. C, sent specimens from Basic 

 City, Va., &*tating 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 

 ( Mancasdius 



water-cress sdwbug 

 bra<iij/urii.<). En- 



larged (after Riehardsov) 



METHODS OF CONTROL. 



Three Avays 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 2)laced at our disposal by Messrs. B. Bryan 



