LIFE HISTORY AND HABITS. 21 
When these larvae are exposed to a moderately subdued light they 
color quite rapidly and become noticeably yellow all over their 
bodies ui a day's time. When the newly hatched larvae are kept in 
darkness they color more slowly, and two or three days elapse before 
their bodies become yellowish. Their skin is quite tender, but in 
spite of this they can survive rather rough handling. 
REARING CAGES USED. 
Several styles of cages were used in an endeavor to find one in 
which the wireworms could be successfully reared and at the same 
time watched. Only three types gave any promise of success, and 
these will be reviewed briefly. 
The first type used was simply a petri dish with damp filter paper 
in it. Several sheets of filter paper were used so that when the 
larvse crawled between the sheets it w^as almost the same as if they 
were in damp soil. Slices of beets were placed in the cage and 
renewed daily. These were of use not only as food for the wireworms, 
but they also assisted in keeping the atmosphere of the dish damp 
and cool. These dishes were then kept in insect boxes to insure per- 
fect darkness and to assist in keeping the temperature even. This 
style of rearing cage was very successful for the first two weeks, and 
much was expected of it, but from that time on one bad point after 
another presented itself, and within a month the cage was given up 
as impractical. The two worst points in connection with this cage 
are that the amount of moisture can not be regulated and, secondly, 
that there is no drainage and the cage tends to foul easily. The 
cages were cleaned every day and fresh filter paper added, but in 
spite of all these precautions a red bacterium (PL VIII, fig. 1) made 
its appearance in several of the cages at about the same time, and as 
there seemed to be no way to check it this style of cage was given up. 
Another rearing cage (fig. 5) which was used was made of plaster 
of Paris, and was patterned after the Janet ants' nest, except that it 
was more simple. It is a plaster-of-Paris block with two depressions 
in it. Water is kept in one and the wireworms in the other. The 
water readily soaks through the block, and if the dish is covered 
with a tight-fating piece of glass the depression contaming the w^ire- 
worms is kept damp and cool. The cage is further improved b}' 
painting the glass plate black to exclude light. Dr. Chittenden sug- 
gested a coating of paraffin for the outside of the dish to cut down 
the excessive evaporation. This scheme worked well where only 
part of the dish w^as coated. Whenever the entire outside of the cage 
was coated, however, the drainage was cut off, the cage became foul, 
and the wireworms died. The great advantage of this cage, as 
pointed out by Messrs. Knab and Dimmock, is that it can be sterilized 
simply by heating. Most of the first trials of this cage were failures. 
