April, '15] 



McCOLLOCH: DUST FOR CORN-EAR WORM 



211 



entl}' prevented some of the eggs from hatching. Practically all of 

 the eggs on the unsprayed branches hatched while 10 per cent or more 

 of those on the sprayed branches failed to hatch and dried out. Ba- 

 rium-sulphide is fuU}^ as caustic and objectionable as hme-sulphur; 

 so far as we have been able to determine, it keeps indefinitely; that is, 

 we have had it for more than a year and it has not decomposed yet. 

 Upon long exposure open to the air, it will gradually oxidize and a 

 fine powdery substance accumulates on the outside of the crystals 

 which amounts to a very small percentage after standing for more 

 than four or five months. 



Mr. T. B. Symons: I presume it would have about the same 

 effect on leaf curl as hme-sulphur. 



Mr. W. M. Scott: The fact that it has done everything that 

 lime-sulphur has done in all of the experiments would lead us to 

 believe that it would act about the same on leaf curl, although we have 

 not had an opportunity to try it on that disease. We sent some to 

 California and Mr. Foster made some experiments on lemon trees for 

 red spider and other mites, comparing it with, lime-sulphur solution. 

 He obtained something like 98 per cent efficiency in controlling the 

 citrus red spider and there was no injury to the foliage, while lime- 

 sulphur solution applied at the same time scorched the foliage. It 

 looks as though there is a promising field for this material in citrus 

 spraying. 



Mr. p. J. Parrott: In regard to the fungicidal properties of 

 barium-sulphide, I ^dll say that we used it in solution last spring with 

 satisfactory results to control apple scab. 



President H. T. Fernald: The next paper will be read by J. W. 

 McColloch. 



RECENT RESULTS IN THE USE OF DUST SPRAYS FOR CON- 

 TROLLING THE CORN-EAR WORM 



By James W. McColloch, Assistant Entomologist, Kansas Agricultural Experiment 



Station 



The corn-ear worm {Heliothis ohsoleta Fab.) has long been recognized 

 as one of the most difficult of the staple crop pests to control. A 

 study of its life economy shows that there are a number of factors in 

 the life cycle of this insect that are prohibitive of complete control 

 and that the best that can be hoped for is a material reduction in the 

 amount of injury: first, the larvae feed almost entirely within the curl 

 of the corn plant or within the ear where they are inaccessible to 

 parasitic enemies and where as. yet it is impossible to reach them with 

 a spray; second, the larvae are able to feed and develop on a wide 



