60 THE SUGAR-BEET WIREWORM. 



])eets and \dre worms were killed. It was used several times more, 

 and in weakened solutions, but invariably the results were the same. 

 By this time the season was so far advanced that experiments along 

 this line had to be given up for the year. The conclusions that seem 

 justified from this experiment at the present time appear to be that 

 the wdreworms may be killed by applications of a solution of potassium 

 cyanid to the soil, but that the beets are also killed by the same treat- 

 ment. It is a question whether a certain strength of cyanid can be 

 found whicli wiU kill the wireworms and spare the beets. Possibly, 

 however, the wireworms can stand a stronger application of the 

 cyanid than the beets can. As this is the only insecticide which has 

 given promise of good results against the wireworms, it will receive 

 further careful tests. The possible effect of this cyanid on the soil 

 and future crops is also an interesting question, and one which wiU 

 have to be investigated. There is a possibility that this cyanid 

 might be applied directly after the crop is removed and before the 

 wireworms have become dormant for the winter. 



EXPERIMENTS WITH POISONED BAIT AGAINST THE WIREWORMS. 



In the experiments in the use df poisoned bait against the wire- 

 worms the points wliich were chosen for solution were, (1) to find a 

 substance for tlie bait wliich would be very attractive to the wire- 

 worms, and (2) to find a poison to go with it whicli would certainly 

 kill the larvae. Thus far success has not been attained in the solution 

 of either. The following materials have been experimented witli as 

 bait: 



Beans. Bran. 



Com. Alfalfa meal. 



Commeal. Shredded beets. 



Of these the only ones which have proved attractive enough to be 

 used with the poisons were beans, corn, and shredded beets. Series 

 of experiments were conducted using each bait witli every poison, 

 and checks were employed in each. The following poisons were used: 



(1) Lead chromate. (4) Paris green. 



(2) Potassium cyanid. (5) Lead arsenate. 



(3) Strychnine. (6) Zinc arsenile. 



The first four named, being insoluble, were applied to the bait in 

 paste form with flour. In the case of every poison except the cyanid 

 the wireworms were observed eating the bait, and if they suffered 

 any ill effects from it they failed to show it to a noticeable degree. 

 The bait containing the cyanid was eaten sparingly on account of 

 its deterrent qualities. Wireworms were found dead in some of the 

 cages in wliich potassium cyanid was used, but whether theii- death 



