LIFE HISTOEY AND HABITS. 29 
RELATION BETWEEN INJURY IN THE BEET FIELDS AND THE SIZE AND 
ABUNDANCE OF WIRE WORMS. 
As is the case with practically every destructive insect, the greatest 
harm is done by the maturing larvas. It is therefore only a matter 
of watching the progress of injury in the beet fields to tell whether 
or not there are many mature wireworms, and whether, therefore, 
there will be an abundance of beetles the following year. In every 
year during which observations have been made thus far it has beer 
a simple matter to foretell tliis point. In 1911 injury to the beets 
was quite heavy and general. From this it was reasonable to sup- 
pose that there were many mature wireworms in the soil and that 
the next year would see an abundance of beetles. Such proved to 
be exactly the case, and beetles were quite common in the fields; 
so much so, in fact, that it was no extraordinary feat to collect over 
25,000 of them for the rearing work. In 1912, in the Adcinity of 
Compton, the wireworm injury, while quite general, was light, and 
using the same reasoning it was probable that there would be few 
beetles in the spring of 1913. This has been partially proven by the 
fact that very few of the larvae taken in the fields during 1912 pupated 
the same fall. The 300 wireworms collected in the summer of 1911 
produced ahnost as many pupae in the fall of that year as the 12,000 
wireworms collected in the summer of 1912 produced during the 
succeeding fall. 
MOLTING OF THE WIREWORMS. 
The wireworms molt in their channels, and wriggUng from their 
old skin (PI. Ill) they lie still for some time until their new skin has 
hardened. If the channel is larger in cross section at the place 
where the wireworms molt, it is so Httle larger as to be almost unno- 
ticed. When ready to molt the larvae he still for some time, in cer- 
tain cases for several days, before the skin spUts and they are able 
to free themselves. In a majority of the cast skins noted the skin 
had spht down the dorsum of the thorax. Where this occurs the 
process of molting is simple and seldom takes more than two or 
three hours. The cast skin is also in one piece. Now and then the 
skin spUts irregularly, and in these cases the molting process requires 
more time, sometimes several days. In one case noted the wireworm 
shed the skin from its head a fuU week after it had molted on its 
thorax and abdomen. In such cases the skin is quite apt to be torn 
into several pieces and is almost useless for study. 
Directly after molting the wireworm, with the exception of its 
mandibles, is a rather shiny opaque white. The mandibles are yel- 
lowish, shading to brown at the tips. The wireworms color quite wel] 
in from one to three days, but they often remain quiescent for weeks 
