REMEDIAL MEASURES. 51 
Slingerland.^ These experiments from the first gave entirely nega- 
tive results, as the beetles could not be induced to feed on any kind 
of foliage, either in the poison or check cages. Further experiments 
were carried on, using such substances as bran, shorts, alfalfa meal, 
and ground beet roots. The last bait was the only one which gave 
any promise, and this proved successful only under laboratory 
conditions. Where the poisoned bait was applied in the cages a 
few beetles were killed by it, but where it was tested in the field it 
gave negative results. This was probably on account of the light 
, feeding habits of the adults and the abundance of food in the fields. 
The poisons used in the bait were Paris green, arsenite of zinc, arse- 
nate of lead, and strychnine. 
FALL PLOWING FOR DESTRUCTION OF THE PUPJE. 
The destruction of the pupse by cultivation, while probably it 
has never been tested under field conditions, has been recommended 
b^^ many students of this group because it is directed against the 
most helpless stage of the insect. From observations made of the 
results obtained by disturbing pupae in the laboratory cages, there 
can be no doubt that this remedy would prove beneficial, since not 
only would it break open many cells and kill the pupae mechanically, 
but 3't would also disturb the rest so that they would come out earlier 
in the spring and be subject to the attacks of their bird enemies. 
This fall plowing would have to be quite deep (9 to 10 inches), and 
very thorough, to be effective. 
The main objection to this remedy is that three or four years 
must elapse before the benefits derived from it become apparent. 
One point will serve to illustrate this. It was reported through 
Mr. R. S. Vaile, the horticultural commissioner of Ventura County, 
Cal., that in one instance, in a field which had been fall-plowed, the 
wireworms were worse than in any of the surrounding fields. This 
was doubtless true, and would have been possible had the plowing 
killed every pupa. The wireworms which do the main damage for 
at least the next two years are already in the soil at the time of the 
plowing and are unaffected by it. This is true because the wire- 
worms are not of sufficient size to be very injurious until the third 
year. Mr. Vaile states that it is a rule with many of the bean grow- 
ers in his county to fall-plow their fields; and that any benefits which 
might have resulted from such a treatment have never been notice- 
able. He adds, however, that the thoroughness of this plowing 
might be improved upon in many cases. 
1 Bui. 33, Cornell Agr. Exp. Sta., 1891. 
