10 BULLETIN 1487, U. S. DEPARTMENT OF AGRICULTURE 
DATA OBTAINED FROM FIELD COLLECTIONS OF oe 
OF APANTELES MELANOSCELUS 
The extent of the hyperparasitism to which A. melanoscelus is sub- 
ject, and the relative paucity of the Apanteles that survive to become 
adults, as indicated by the field-collected cocoons under observation, 
were very surprising. A summary of the more important records 
powers the monthly collections previously referred to is given in 
able 1. 
TABLE 1.—Summary of records obtained from the monthly collections of Apanteles 
melanoscelus cocoons made from June to October over a three-year period, from 
three localities 
! | 
| | 
| | Cocoons producing 
Cocoons producing | Cocoons producing | neither ‘Apanteles. 
Total adult Apanteles hyperparasites | mor  hyperpara- 
F | Sites 
Collection | cocoons fee 
‘Number Per cent | Number Per cent | Number | Per cent 
| 2 ae ais easel 
iMmirst-generavion= =.= <2 es 2, 164 614 28. 4 1, 148 52.8 407 | 18. 8. 
Second generation No. 1_________| 2, 201 597 PAGAL 977 44.4 627 | 28. 5 
Second generation No. 2_-_______ Dole 37 1.6 981 42.4 1, 294 | 56. 0 
Second generation No. 3-_--_--_- 2, 224 1 20 845 38. 0 1, 367 | 61.5 
Second generation No. 4--__-_-- 2, 008 11 Bey 274 | 13.7 1, 723 85. 8 
Note.—The collections contained 220 to 250 cocoons. Figures given cover nine collections of first-genera- 
tion cocoons and nine collections of second-generation cocoons for each month from July to October, inclu- 
sive, which are numbered, respectively, 1, 2, 3, and 4. 
The collections of first-generation cocoons produced the highest 
proportion of Apanteles, 28 percent. This may be slightly lower than 
actually occurs in the field, for most of these cocoons were obtained 
after a large part of the adult Apanteles of this generation had already 
emerged, and those, of course, are not taken into account, since only 
cocoons without exit holes were collected. On the other hand, cer- 
tainly some of the cocoons from which Apanteles emerged several © 
days after collection would have been parasitized had they remained 
in the field. Accordingly, 28 per cent is probably not far from the 
proportion actually produced in nature. The records on the col- 
lections of second-generation cocoons show clearly that as the season 
progresses the chances that given cocoons in the field will ultimately 
yield Apanteles adults rapidly diminish. The first collections of 
second-generation cocoons were made within two weeks of the time 
that the first of these cocoons were being formed and before all the 
Apanteles larvae had completed their development. In this case the 
proportion of cocoons producing adult Apanteles was about the same 
as for the first generation. Both lots of cocoons had been exposed to 
hyperparasites only a very short time. Less than 1 per cent of col- 
lections 3 and 4 of second-generation cocoons, which were obtained in 
September and October, produced Apanteles adults. The figures for 
these late collections have particular significance, for they represent 
more exactly than the data covering the other collections the real 
condition of the Apanteles cocoons that are to carry this important 
primary parasite over the winter. 
It is possible that the cocoons collected were the more exposed ones, 
and that these would be most heavily parasitized. On the other 
hand, the figures on these cocoons do not take into account any dam- 
