1917] Wilcox—Rearing Insects for Experimental Purposes | 
Battery Jars. 
Battery jars (PI. III, fig. 1) with pieces of glass for covers have 
been quite useful for rearing some insects. The glass covers en- 
sure a high humidity and this naturally keeps the food fresh. Such 
jars were found to be very satisfactory for rearing silkworms, 
many hundred having been reared during the summers of 1915 and 
1916. 
Sand was placed in the bottom of the jars. During damp 
weather, or when there was an excess of water of condensation, the 
covers were removed to facilitate evaporation. Silkworms, as is 
known, do not ordinarily leave their food, so the covers could be 
removed with impunity. 
For rearing wood-boring insects, the battery jars have also been 
found very useful. 
: Trays. 
Several types of trays, designed at the Gipsy Moth Laboratory 
at Melrose Highlands, Mass., have been used quite extensively in 
rearing gipsy moths during the past few years. I have used trays 
of various sizes and shapes. The trays (PI. III, fig. 2) were usually 
made entirely of cardboard or wood with cheese-cloth or paraffin 
paper bottoms. ‘To prevent larvee from escaping, the edges of the 
trays were smeared with tangle-foot. These trays are used ex- 
tensively, but when a large number of larve are reared in a single 
tray, some difficulty is experienced, for the larvee often get caught 
in the tangle-foot and eventually form a bridge over which others 
escape. The tangle-foot must be repeatedly combed or stirred 
with a stiff brush. This cleans the tangle-foot and also forms 
ridges over which it is difficult for the larvee to escape. 
Diseases frequently develop and the mortality is generally high 
in such trays. 
Riley Cages. 
I have used a modified type of the Riley cage built for the Gipsy 
Moth Laboratory, with considerable success. The frames are 
built of wood, covered with a fine wire mesh. They are provided 
with removable wooden bottoms and have a door on one side. 
The cages are sixteen inches square and twenty-four inches in 
height. 
Considerable material, especially Cerambycids and their para- 
