50 
were only a few, died from disease. The exact mortality ratio was, 
therefore, 98.08 per cent. 
In the later months of 181)0 the abundant presence of hyperparasites 
was made manifest. Many hundreds of specimens of Dibrachy^ bou- 
cheanus were reared from the cocoons of the Pimpla, and while the 
next most important primary parasite. Ghal-eis ovata, has not definitely 
been proved to have its own parasites, it is almost safe to state that 
it also is destroyed by this species or some other of the secondary 
parasites. The other primary parasites, notably Meteorus communis, 
Limner la raliria. and the Apanteles, were also, almost without excep- 
tion, destroyed by hyperparasites. principally Spilo chalets debilis and 
IHbrachys boucheanus. 
The effect of this hyperparasitism began to be noticed by the time 
the third generation of tussock-moth caterpillars became full grown. 
It was no longer so difficult to find specimens as it had been in June. 
They were still rare, however, and the number of e<ig masses laid in 
the late autumn at the points where these studies were carried on was 
very small. 
The length of time which it will take the Orgyia to recover from this 
exterminative parasitic attack can not be surmised. The partial recu- 
peration toward the close of 1896 was a matter of some surprise, and 
must be attributed almost entirely to the work of hyperparasites. 
Ordinarily recovery from a severe case of parasitism following an 
undue multiplication of lepidopterous larvae is rather slow, as is 
instanced by the published records regarding the army worm [Leucania 
unipnncta). 
We should naturally have expected a period of abundance of tertiary 
parasites to have followed that of the secondary parasites. This, how- 
ever, was not the case. Tertiary parasitism seemed to be comparatively 
rare and was only definitely proven in the case of Asecodes albitarsis 
and Dibrachys boucheanus, the latter being usually a secondary parasite. 
The majority of the specimens of the Asecodes issued in the late fall 
and early winter of 1895-90. There must be a limit to this work of 
parasite upon parasite at some point, and it seems certain that tertiary 
parasitism is rare, and that quaternary parasitism seldom occurs. An 
interesting fact was, however, noticed in the late fall and early winter 
of 1890, and that was that many of the parasitic larva 1 died apparently 
as the result of disease, although possibly from some other cause — as, 
for example, the puncture of a hyperparasite, the larva* of which did 
not develop. A number of dead larvae of Pimpla inquisitor and Dibra- 
chys boucheanus were found in the Orgyia cocoons in December, 189(>, 
more or less shriveled and slightly moldy, but apparently whole. 
It must be stated that nearly all of the observations which Ave have 
recorded were made on or in the immediate vicinity of the grounds of 
the U. S. Department of Agriculture, and that observations made inci- 
dentally and by no means with the same thoroughness in other parts 
of the city show that conditions vary in neighboring localities, and that 
