REMEDIAL MEASURES. 61 
was due to eating the poison or to the effect of fumes has not been 
determined. 
The results in the use of strychnine and potassium cyanid have 
Jbeen quite well verified in an entirely independent series of experi- 
ments carried on by Mr. U.S. Vaile. 
From the foregoing it can be seen that the experiments thus, far 
tried in the use of poisoned bait against the sugar-beet wireworm 
have been far from satisfactory. They are to be continued in future 
work. 
EXPERIMENTS WITH GUANO FERTILIZER. 
The only fertilizer tested on the wireworms was a mixture of bird 
and bat guano, a South American product, wliich is chiefly nitroge- 
nous and is characterized by a strong and lasting odor of ammonia. 
It was hoped that the strong ammonia odor would drive the wire- 
worms deeper into the soil. The results from its use thus far — it 
has been tried only on a small scale in the laboratory — seem to indi- 
cate that it would have to be used at the rate of from 8 to 10 tons 
per acre to be partially effective. As this is many times heavier 
than an average dressing for the soil it would probably be impractical 
to use it. 
PROTECTION OF BEETS BY EARLY PLANTING. 
The protection of beets by early planting is a remedy wliich was 
early suggested by Mr. H. M. Russell and has since been given a 
practical test on a large scale. The advantage of tlus method is 
very plain. Wlien the beets are planted early the plants are quite 
hardy and the roots are swollen by the time the wireworms are doing 
their worst injury. (See PL XIX, fig. 1.) These swollen roots can 
stand a severe attack without having their sap supply cut off, and in 
consequence a much smaller number of them are killed. 
Mr. H. J. Mayo, one who grows sugar beets on a large scale in both 
Los Angeles and Orange Counties, writes as foUows concerning early 
planting : 
* * * In the season of 1911 I planted early and the results were very good, 
especially on the heavy land, as the beets seemed to get a start, and the worms did not 
seem to affect them so much, although they were in the groimd and from examinations 
that I made they worked on the beets; but where the beets got the start the worms 
did not bother them so much. 
In my opinion early planting will relieve a great deal of the danger of the wireworm. 
Clean Culture against the Adults. 
The following in regard to remedial measures is the result neither 
of theory nor of experiment. It was suggested to the writer by 
observations taken in the field at the time the hibernating beetles 
