REMEDIAL MEASURES. 
63 
B 
where they could find shelter or to remain where they were, exposed 
to the attacks of their predaceous enemies, the birds. In the instance 
cited probably many were eaten by birds, as these were quite abund- 
ant at the time, and the fields were bare. 
In the observations dealing with the dispersal of the beetles 
throughout the fields it was determined that for the greater part the 
beetles remain and lay eggs near the place where they have been 
feeding. From this it is easy to see that in the fields which contain 
the greatest number of old beets and beet tops the largest number of 
beetles wiU deposit their eggs. As the wireworms can not travel 
very far from where the eggs are laid it is readily seen that large 
numbers of beetles in a field are the forerunners of large numbers 
of wireworms in that field later, with their resulting injuries to the 
crop. 
A condition leading to the successful hibernation and dispersal of 
wireworms is illustrated in Plate XXIII, figures 1 and 2. In these 
instances the immediate proximity of alfalfa fields to those containing 
beets affords effective shelter for 
the hibernating beetles, and, as 
alfalfa is only second as a host to 
beets, provides abundant food for 
a continual supply of larvse and 
adults. Reinfestation under such 
conditions is naturally very Hkely 
to occur through the migration of 
the beetles from the alfalfa to the 
beets, and both crops may thus 
be injured. 
The main drawback to clean cul- 
ture is that even where it is prac- 
ticed faithfully several years must pass before positive results wiU 
be apparent. As has been stated, the same thing is true with regard 
to fall plowing for the destruction of the pupae. This would be 
advantageous in one way, however, in that the benefits would be felt 
for two years after the treatment had been discontinued. The main 
difficulty is that a grower, after practicing this remedy for two years, 
might suffer heavily from wireworm injury, become discouraged, 
and stop the treatment. The only way to give this remedy a fair 
trial would be to practice it faithfully and wait until the third or, 
better, the fourth year before drawing conclusions. 
The greatest advantage of this remedy is that it is entirely feasible 
and, being cultural in character, is also entirely practical, regardless 
of the crop grown. For the best results it should be practiced in 
conjunction with faU plowing, and to reduce the injury from the 
wireworms already in the soil early planting should be employed. 
F/ELO 
Fig. 9.— Diagram of beet fields, to illustrate the 
effect of clean culture in reducing injury by the 
sugar-beet wireworm. (Original.) 
