210 
IOWA ACADEMY OP SCIENCE 
The parasitism of Phlegethontius by Apanteles congregatus was first recorded 
by Pitch (1865), who reared this parasite from larvae of Phlegethontius guinque- 
inaculata. Say (1835) in describing the species, said that he reared it as a 
parasite of a Sphinx larva. Since then this Apa^iteles has been reared by 
many entomological writers. 
In the fall of 1906 I secured several tomato-worms that were literally covered 
with these small, white cocoons, and reared two species of parasites from 
them. Rather strange to say, neither of these Wo parasites were the makers 
of the cocoons. Both of them were hyperparasites^ which had deposited their 
eggs in the cocoons of the primary parasite after these had been formed on 
the outside of the tomato-worms. The host larvae, the tomato-worms, were 
collected at Urbana, Illinois, September 25, 1906, by Mr. J. L. Pricer, and the 
parasite cocoons from these larvae were removed and placed in small vials 
in the entomological laboratory of the University of Illinois. 
The first of these hyperparasites to emerge was a delicate, light brown 
species, Mesochorus luteipes (Cresson), so determined for me by Mr. J. C. 
Crawford, of the U. S. National Museum at Washington. Soon afterwards a 
small chalcid began to appear from the cocoons. This chalcid is the same 
species described years ago by Pitch and called Pteromalus tadacum. Mr. A. A. 
Girault, however, writes me that this is really Hypopteromalus viridescens, 
described by Walsh. No specimens of the primary parasite, Apanteles con- 
gregatus, were reared at all from this lot of cocoons, and for a long time the 
writer thought that the Mesochorus was the primary parasite. 
On October 1 two specimens of Mesochorus luteipes appeared in the vials, 
and from October 1 to 8 this species emerged abundantly. In leaving the cocoon 
they cut an irregular, jagged hole near the end of the cocoon, usually at the 
side of the end. 
On October 10 the chalcid, Hypopteromalus viridescens, appeared in the 
vials. The vials were kept in warm laboratory rooms through the winter and 
the chalcids. continued to emerge. On December 28 two specimens of the 
Hypopteromalus emerged; on January 16, one specimen of Mesochorus ; and 
on January 26 the Hypopteromalus were again coming out of the cocoons. 
As late as Pebruary 11 there was found in one vial a single dead Mesochorus 
luteipes, which could not have emerged many days before. 
Pitch (1865) observed this chalcid, and he described it under the name of 
Pteromalus tahacum, correctly interpreting it as a hyperparasite. As such it 
has since been mentioned by Glover (1874) and by Garman (1894) (1897). 
So far as I know, Garman (1894) (1897) is the only one who has recorded 
Mesochorus luteipes in its relationship to Apanteles congregatus. 
No further observations Vv^ere made by the writer on these parasites until 
the fall of 1910, when an abundance of the tomato-worms at Ames brought 
with it a corresponding abundance of the primary parasite, Apanteles con- 
gregatus. Large numbers of these Apanteles cocoons were collected and 
brought in to the insectary, where they were placed in vials in the insectary 
cold room. These vials were examined daily in the fall until late in October, 
and in the spring from about the middle of March on. This was done to 
determine how the parasites spent the winter, and to find out something about 
the relative abundance of the primary parasites and those which were secondary. 
