14 SOME INSECTS INJURIOUS TO TEUCK CROPS. 



To make the work thorough, water should uot be turned into the trench again 

 for twelve or twenty-four hours, in which time the few bugs left among the 

 cress stems will die or find their way to the trough. The trenches can be cleared 

 of bugs in warm weather as frequently as desired, but less danger is done the 

 cress crop if the work is done just after gathering the cress. 



The same method of disposing of the sowbugs could be used in greenhouses 

 in the winter, but cress gi'own in the open air could not be exposed in freezing 

 weather, making the remedy inapplicable in cold weather. 



We have not used water in these trenches deeper than 10 inches, and are not 

 able to say how a larger or more rapidly flowing supply of water would act, 

 nor have we grown winter cress in them, as our water supply is insufficient 

 for that purpose. 



OTHER REMEDIES. 



About the only other remedies which we have been able to suggest 

 are the use of a substance, such as sulphate of copper or chloric! of 

 lime, which might be placed in the water to destroy the pest. As 

 the former has already been tested by Messrs. B. Bryan & Son (see 

 page 13), it need not be mentioned further. 



Mr. John H. Reed states that a grower at Healing Springs, Va., 

 has a remedy consisting of a poisonous material which is placed in 

 the water, but he does not know the ingredients nor whether there 

 would be danger to stock drinking the water below the spring. He 

 writes also of the possible use of chlorid of lime. A tank of bleach 

 composed principally of chlorid of lime ran into a creek at Mount 

 Holly Springs, Pa., killed everything that was living in that stream 

 for about half a mile downward, but did not poison stock that drank 

 the water. The bleach came from a paper-mill tank which had 

 burst. If chlorid of lime is tested it should be used on a very small 

 scale at first to note the effect on plant life. It is apt to be harmful 

 to trout and other fish present. 



Mr. Reed also suggested the employment of ducks to destroy the 

 pest, but this would necessitate the abandonment of cress culture for 

 a season, as the ducks would injure the condiment both by eating it 

 and by fouling the water. 



Among other remedies, we have recommended draining off the 

 water where possible and exposing the sowbugs to the drying effects 

 of the sun. 



FISHES AS A POSSIBLE MEANS OF DESTROYING THIS ISOPOD. 



In response to inquiry, the following information was received 

 from the Bureau of Fisheries, through Mr. Lawrence O. Murray, 

 Acting Secretary, Department of Commerce and Labor, in regard to 

 the fishes which might be found useful in the destruction of this 

 aquatic isopod in its occurrence on water cress : 



Among the fishes which would probably prove most useful for this purpose 

 and with which it is suggested that the Department may wish to experiment 



