Apr. 1, 1925 
Two Imported Egg Parasites of the Gipsy Moth 
665 
In order to handle the eggs in a 
satisfactory manner it was necessary 
first to separate them from the mass 
of hairs in which the female moth had 
packed them. This was originally 
done by rubbing the egg clusters with 
the bare hand or with a pad over a 
piece of cotton cloth, drawn tightly 
over a tray, as in Figure 7, d, until the 
hair had been rubbed through the 
cloth, leaving only the eggs on the 
cloth. A machine on the principle of 
the gristmill is now used to do this 
sifting. This machine, shown in Fig¬ 
ure 9, a and 5, has two disks about 3 
feet in diameter, the lower one of which 
is stationary, while the upper revolves, 
the power being furnished by a small 
motor. The inner surface of each disk 
is padded with felt covered by canvas. 
The upper disk rests on a spindle, and 
can be adjusted so as not to injure the 
eggs. The broken egg clusters are fed 
into the machine through a boxlike 
opening in the upper disk; as this disk 
revolves the eggs are gently rubbed 
between the two inner surfaces. As 
the eggs are worked to the circumfer¬ 
ence of the disks they become sepa¬ 
rated, cleaned, and drop off, assembling 
in a jar below (fig. 9, a). The hair and 
dust from the egg clusters are removed 
by means of a blower attached to the 
center of the apparatus. 
This apparatus is not only a great 
labor saver, but by cleaning the dust 
and hair from the eggs it eliminates to 
a large extent the irritation of the nose 
and throat, which has at times severely 
affected most of the men at the 
laboratory. 
After the eggs have been cleaned 
(fig. 7, f) they are ready for the sepa¬ 
ration of the parasitized eggs. For¬ 
merly the eggs were placed in trays 
(fig. 7, b) until the hatching of the 
nonparasitized eggs was completed. 
The cleaned eggs were spread evenly 
over the bottoms of the trays. In the 
front of each tray are numerous 1-inch 
holes, the use of which will be explained 
later. In each tray, on top of the 
layer of eggs, was placed one or two 
thicknesses of cloth mosquito netting, 
through which the small caterpillars 
had to crawl on leaving the tray. A 
considerable part of the web spun by 
the crawling larvae was caught in this 
netting (fig. 7, c). When the eggs and 
netting were in place each tray was 
entirely covered with black paper and 
placed on racks in a warm room to 
allow the nonparasitized eggs to hatch. 
Before it was time for the eggs to hatch 
the paper was broken over the holes 
in the front of each tray and glass 
vials were inserted (fig. 7, 6), into 
which the caterpillars crawled. When 
hatching began the entire attention of 
several men for nearly two weeks was 
required to remove the larvae from 
the glass tubes. This was best accom¬ 
plished by cleaning out each tube with 
a camel’s-hair brush and placing the 
caterpillars in kerosene. This method 
was later much improved upon by using 
a vacuum cleaner with a special attach¬ 
ment which fitted into the tubes. 
After hatching was completed the 
black-paper tops were taken from the 
trays and the mosquito netting was 
removed, with much of the webbing 
left by the crawling caterpillars. The 
remaining material was separated as 
well as possible by allowing the air from 
an electric fan to pass over it, blowing 
out some of the eggshells and light, dead 
eggs. This separating process was 
greatly improved by the development 
of a machine (fig. 9, d) so constructed 
that as the parasitized eggs, dead eggs, 
and eggshells ran down a chute the 
dead eggs and eggshells were drawn off 
by suction, while the parasitized eggs, 
which are heavier than the other mate¬ 
rial, assembled in a glass tube at the 
bottom of the apparatus. 
This method of allowing the non¬ 
parasitized gipsy-moth eggs to hatch 
so that the parasitized eggs could be 
separated from the rest of the material 
was a long and tedious process and has 
been discontinued except for small ex¬ 
periments. Now a simple apparatus 
called a bouncing machine (fig. 9, c) is 
used. The eggs are allowed to run 
down a wooden chute, at the bottom 
of which is a small piece of tin placed 
at right angles to the inclined sur¬ 
face. This piece of tin is termed a 
“take-off”; when the eggs hit it they 
bounce into the compartments of a 
box beneath. The eggs containing 
parasite maggots do not have the same 
capacity for bouncing as the healthy 
gipsy-moth eggs and therefore fall into 
the first and second compartments, 
while the other eggs bounce farther and 
drop into the compartments beyond. 
The nonparasitized eggs are then 
destroyed. The eggs containing para¬ 
sites are put into small manila enve¬ 
lopes in lots of about 1,000 parasites 
each for colonization in the spring. 
These parasitized eggs are not actually 
counted, but are measured in a small 
glass tube so graduated that each 
colony will contain 1,000 eggs. 
COLONIZATION OF ANASTATUS 
The first colonization of Anastatus 
in America was made in 1908, when 513 
adults were liberated. Most of these 
19977—25f-6 
