38 



BULLETIN 124^, U. S. DEPAETMENT OF AGBICTJLTUBE. 



was again too high, and a large enough number of worms were not 

 killed to justify the expense incurred. 



ROLLING AND BRUSH DRAGGING. 



At the time a field is being damaged by the worms the hay that 

 remains undestroyed can be cut and then either a brush drag or a 

 roller run over the ground, by which a great many of the larvae will 

 be destroyed. Some experiments tried along this line by Mr. T. 

 Scott Wilson were quite successful. On August 15, in a 5-acre patch 

 a brush drag was used and a great many larvae were killed. This 

 field was overrun by Bermuda grass, which protected many larvae 

 that would have been killed. A roller here would doubtless have 



Fig. 20. — Brush drag used to crush alfalfa caterpillars in the fields. (Original.) 



mashed all larvae. On the 26th of August another test was made, 

 using the same drag. In this case the larvae were about full grown, 

 and 55 per cent were killed by the operation. The latter experiment, 

 however, was carried on in alfalfa of considerable height, and con- 

 sequently the larvae were afforded much protection and as large a 

 percentage was not killed as would have been the case had the drag- 

 ging immediately followed cutting. 



A good brush drag and one that is well adapted to dragging 

 alfalfa is shown in figure 20. The plan for constructing this, as 

 given by Mr. E. S. G. Titus, in Bulletin No. 110 of the Utah Agricul- 

 tural Experiment Station, is as follows : 



The drag is niade by laying the butts of rather short brush, five or six feet 

 long, in a row on a plank twelve or fourteen feet long, then another row should 



