194 
Journal of Agricultural Research 
Vol. XIV, No. 5 
competition between the different parasitic species hibernating in the 
brown-tail-moth larvae. Still other information obtained by opening 
the webs and dissecting caterpillars is that on “winter-killing” among 
the brown-tail-moth larvae, and the relation of parasitism to this phe¬ 
nomenon. Very low temperatures act as an important control agent 
in the more northern parts of the brown-tail-moth area in Maine, New 
Hampshire, Vermont, and parts of Massachusetts. It might be ex¬ 
pected that caterpillars infested by parasites would succumb more 
quickly to the cold, and that thus the low temperatures would act as a 
proportionately greater check upon the parasites than upon the brown- 
tail moth larvae. Fortunately this does not appear to be the case. The 
parasitism in webs containing a large percentage of dead caterpillars is 
scarcely, if at all, less than in webs from the same locality with few 
dead larvae. Dead caterpillars, as found in the webs, are usually dried 
up and unfit for dissection, but when dissections have been possible the 
dead larvae showed no abnormally great parasitism. The probable reason 
for this is that the hibernating parasites are very small and have made 
no great inroads upon the reserve food of the host larvae, their feeding 
having been slight at most and extended over a considerable period, so 
that the caterpillars have not been materially weakened. 
APANTELES LACTEICOLOR VIERECK 
The species of Apanteles that hibernates in the young caterpillars of 
the brown-tail moth was described by Viereck in 1911 (7, p . 475) from 
material reared at the Gipsy-Moth Laboratory, Melrose Highlands, Mass., 
as “ Apanteles lacteicolor .” That so widespread and so general a parasite 
of the brown-tail-moth caterpillars in Europe should not have been 
described before is somewhat surprising, and it may yet be found 
that the insect has been described, but too imperfectly to be recognized 
thereby. Meanwhile the name “Apanteles lacteicolor Viereck” must 
stand. 
As Viereck’s description is very brief, a fuller characterization is 
given herewith. 
Male and female. —Length 2.5 mm. Black; head including the antennae 
black, covered with a short sericeous pubescence; vertex, front, face, and clypeus 
all finely punctate; eyes hairy; female antennae as long as the body, those of the 
male longer. 
Thorax: Mesoscutum densely, rather deeply punctate; scutel more shining, with 
sparse very shallow punctures, slightly convex; tegulae black. The propodeum is 
very distinct from that of other species of the genus in that it has on the apical 
two-thirds three, one median and two lateral, large shining areas, and a less distinctly 
margined and less smooth almost circular area on each side near the base; the median 
area is pentagonal, while the apical lateral areas are subtrapezoidal, and extend 
slightly beyond the apex of the median area, reaching the posterior margin of the 
propodeum. The wings have the veins generally pale, with the costa and stigma 
brown in the female and only the outline of the stigma brown in the male; the exterior 
vein of the first cubital cell is only slightly angled a little below the middle. Legs: 
