4 BULLETIN. 1201, U. S. DEPARTMENT OF AGRICULTURE. 
Potato-beetle larvce. — Larvae of the potato beetle were collected 
on potato plants and when brought to the laboratory were placed 
in cheesecloth cages, 9 inches square by 12 inches tall. The larvae 
were so well mixed before they were placed in the cages that each 
cage contained about the same number in the various instars. 
Sprayed or dusted potato-plant foliage was given to them daily. 
Parasitism was common only among those in the last instar. 
House flies. — Flies were reared in specially constructed screen- 
wire cages, 12 inches square by 18 inches tall, each of which con- 
tained one-half gallon of moist bran mash. The females readily 
oviposited in this mash, which later served as food for the larva; 
and which proved a good substitute for manure. Lar^e numbers 
of flies were thus reared, some of which were fed poisoned food 
in these cages, while others were transferred to small observation 
screen- wire cages in which they were dusted with powders. 
A i>h ids. — Some of the aphids tested were sprayed or dusted out- 
side the laboratory, but most of them were treated inside the 
laboratory in a manner similar to that described in another paper 
(60, p. 508). 2 
Honeybees. — Twenty young worker bees of practically the same 
age were placed in each of many screen-wire experimental cages 
and were fed in a manner similar to that described in another pub- 
lication (61, p. 181). The sawfly larvae were treated as described 
for aphids. 
Silkworms. — Silkworm larva? were reared in the laboratory and 
were fed leaves as follows: Mulberry-tree leaves were dusted or 
sprayed with the various preparations and with tap water (used as 
a control), an atomizer being used in all the spraying experiments. 
The leaves after having been dried in the air were cut into small 
strips which were then placed in small screen-wire cages. An effort 
was made to put approximately the same amount of food in each 
cage, so that a rough comparative estimate of the food consumed 
could be made: this procedure was also followed while feeding 
the other species of chewing insects. Ten normal silkworms, all 
of practically the same size and not ready to molt, were put in each 
cage. Counts were made daily (except on Sundays), the cages 
being cleaned and treated food being renewed at the same time. 
No disease was noticed among these Larvae. 
Fall webworms. — Webs of the fall webworm were collected in the 
fields on Monday from a variety of plants; after being brought to 
the laboratory, these webs containing the webworms were kept in 
large cages with a small amount of food till Tuesday noon, by 
which time the larvae were well mixed according to size (all instars 
but the first one), and by this time they were very hungry. Tuesday 
morning approximately the same amount of mulberry-tree foliage 
was placed in each of several wide-mouthed bottles containing 
water: it was then sprayed or dusted, and when the foliage was dry 
each bottle with contents was placed in a large battery jar. 8 inches 
in diameter by 12 inches tall. Tuesday afternoon an effort was made 
to place approximately the same number of webworms in each jar, 
? Tlir figures (italic) in parentheses refer to "Literature cited," p. 54. 
