16 
being done by Pimpla inquisitor and Chaleis ovata. In the spring of 
1896 so many of these primary parasites had successfully hibernated 
that they were in position to almost annihilate the first brood of cater- 
pillars, already weakened greatly in numbers by the extensive para- 
sitism of the previous autumn. In the later months of 1896, however, 
an extensive hyper-parasitism began to be effective, and the principal 
primary parasite, Pimpla inquisitor, was almost killed off by its own 
hymenopterous parasites and principally by Dibrachys boucheanus. 
Tertiary parasitism was noticed at this time, but was not especially 
effective, and-the Orgyia had begun to recuperate in numbers at the 
close of 1896. Several careful accounts in July, 1896, showed the per- 
centage of parasitism to be 98.8 per cent, and the numerical details of 
the parasites concerned were found in one instance to be as follows: 
On June 30 and July 8, 1896, 624 cocoons of the tussock moth were 
collected without discrimination from the trunks of trees in the United 
States Department of Agriculture park. From these 624 cocoons issued 
the following parasites: 
Specimens. 
Paumipla: INQuisitor - .s..- .-ose.s2 eset eas See ee eee pee ee ee ee 729 
baswytnr ex “pimple. 0122. hes ee eee oe ee ee 13 
aemrneTia Validea... < 2252-2 Se i ee ee ee 1 
MRETOnIa TUVESCONS .:- = avis 5 Sane es ee ee aloe See ae 1 
WH ONCTS{ON Bb8 a. scan odio Sra eee cea te ea ie ee ne ee eee eee 69 
Dibrachys bouchéanws .¢o5< se. 38 3.2 en cee ee hays ae AS rete eae ae ees noe ee 50 
AISECOUES AlDIGATSIS.. 22):.2- Seed. Sooo noes bes Se De i 
Pronbina aletiae: . 2. i-s. 2 Sas eee eas Bee DERE SUS ek aie) OE TN” Sa ne aes eee Se 7 
Brontinacfrenchil. .oc<26., ch oS ee ee ee 14 
Machina mella......:.,.-«) <2 Seo 5 Soe, ace Coe Se ae oe ae eee eee 12 
Haphorocera claripennis’. .....-.2... <2 s-i.53 eee ee se eg ee eee 15 
Exonista, STISeOMICANG = 22s... oo ok os oe ee ln cease Bee a eee ee 4 
Total 2 coc55 2c So SA ee Re Sree ee 916 
The part played by dipterous parasites up to the winter of 1896, when 
the bulletin in question was published, had not been great, only 187 
specimens in all having been reared. All the species were well-known 
Tachina flies of wide distribution and general parasitism. 
A recuperation in numbers of the Orgyia was quite marked in the 
spring of 1897, and additional and heretofore unreported observations 
were made. So great had been the destruction of Pimpla inquisitor 
that in these observations this species did not appear in a single 
instance! Another hymenopterous parasite, Chalcis ovata, became 
prominent, and it is worthy of note that while secondary parasites of 
this species are strongly suspected, it is not absolutely known to have 
any. A striking feature, however, was the great increase in the num- 
ber of the dipterous parasites. The rearings were conducted on a 
large scale, and the following table affords an interesting comparison 
to the one just given. 
Five thousand larve and pup of Orgyia leucostigma were collected 
