June, '21] HORSFALL AND EVER: MILLIPEDE CONTROL 269 



Mr. R. N. Chapman: Do you ktiow how large a voliime can be 

 passed through this, and at what rate? 



Mr. T. J. Headlee: No. I have not tried to work it out. I have 

 used as high as 5 liters in 10 minutes; that is, a liter every two minutes 



President Wilmon Newell: The next paper is by J. L. Horsfall 

 and J. R. Eyer. 



PRELIMINARY NOTES ON CONTROL OF MILLIPEDES 

 UNDER SASH 



By J. L. Horsfall and J. R Eyer, State College, Penna. 



In the fall of 1910, truck growers in eastern Pennsylvania experi- 

 enced severe losses from the depredations of millipedes. One grower 

 lost his entire stand of carrots and fifty per cent of his stand of let- 

 tuce gro\\'n under sash. Two problems presented themselves: one, 

 the prevention of injury to lettuce in the fall as the seed was germina- 

 ting; two, the prevention of injury to growing tomato seedlings in the 

 spring. 



Control by Soil Fumigants and Contact Preparations 



Eeffect on Millipedes:- In tables I and II the data were obtained 

 from cold frames seeded to lettuce in the fall. All plots comprised an 

 area of 48 square feet. From table I it will be seen that sodium cya- 

 nide at the rate of 150 pounds to the acre, when sprinkled in furrows 

 and covered, resulted in an increase of 256 plants as compared with 

 the check plot. The slight increases in stand in plot Ic and plot Id 

 can hardly be attributed to control of millipedes in view of the fact 

 that these pests damaged the outer rows in all the check plots to a 

 greater extent than they did the center rows. Since the increased 

 number of plants in plot Ic and plot Id were found in the center rows 

 while the side rows had the same stand as those in check plot 1, it is 

 clear that control was lacking. No control was obtained in plots 

 treated with creosote oil, diluted either 1 - 25 or 1 - 50, or with cre- 

 sylic acid 1 - 100. Creosote oil 1 - 100 and cresylic acid 1 - 200 gave 

 some control but this was small when compared with results obtained 

 with cyanide. At the time the counts were made, living millipedes 

 were common in all the plots treated with creosote oil and cresylic 

 acid while few were found in the cyanide plots. 



Two of the treatments applied the day seed was drilled resulted ina 

 decided retardation of millipede activities as shown in table II. On 



