IOWA ACADEMY OF SCIENCE 
211 
Six different lots of Apanteles cocoons, 2,393 cocoons all told, were brought 
in to the insectary at dates ranging from September 7 to October 18. The 
number of parasites of the three species reared from these cocoons is given 
in the accompanying table. 
Lot. Date. No. of Cocoons. Apanteles. Mesochorus. Hypopteromalus. 
1 September 7 172 92 0 43 
2 September 30 364 251 0 13 
3 October 5 373 155 4 147 
4 October 10 261 119 8 57 
5 October 12 773 300 10 338 
6 October 18 450 195 5 181 
Total 2393 1112 27 779 
Figuring out the percentages of the parasites reared, based on the total 
number of cocoons, it is found that 46.4%, less than one-half, of the Apanteles 
cocoons gave Apanteles adults. Nearly one-third, 32.5%, of the cocoons gave 
adults of Hypopteromalus viridescens, while only 1.1% represents the number 
of MesoeJiorus reared. From nearly one-fifth of the cocoons, 19.6%, nothing 
was reared. These cocoons contained either dead larvae or adults of Apanteles, 
occasionally one of the other species of parasites. 
Specimens of both the Apanteles and the MesocTiorus were sent to the U. S. 
National Museum at Washington and examined by Mr. H. L. Viereck, a special- 
ist in parasitic hymenoptera. Mr. Viereck determined the first as Apanteles 
congregatus (Say) and the second as Mesochorus aprilinus (Ashmead). 
It is interesting to compare the figures just given with those of Garman 
(1894), who reared three species of parasites from cocoons on tomato-worms 
collected at Lexington, Kentucky, in 1890. At this time Garman reared 123 
Apanteles, 97 Hypopteromalus and 197 MesocTiorus. Here, then, the secondary 
parasites far outnumbered the primary Apanteles. The species of Mesochorus 
here concerned was luteipes. 
From the cocoons brought in to the insectary at Ames, September 7, nearly 
all the parasites {Apanteles and Hypopteromalus) emerged in the fall, although 
a few of the Hypopteromalus emerged the next spring. Of the parasites in 
this lot the Apanteles emerged first, followed by the Hypopteromalus, after 
an interval of 10 days or two weeks, during which no parasites emerged. 
From those cocoons collected after September 7, occasional parasites of all 
three species emerged in the fall, but no secondary parasites emerged from 
cocoons collected October 10 or later. In the spring, from these cocoons, both 
Apanteles and Hypopteromalus emerged in great numbers, Mesochorus emerg- 
ing sparingly. Comparatively few Mesochorus were reared at all from this 
material. 
The different species of parasites emerged at different times from the vials. 
A second species did not begin to emerge until the first species had ceased 
coming out, so that all of one species emerged in a body, quite separate and 
distinct from the others. In no case were two species found in a vial on the 
same day, and the vials were examined every day while the parasites were 
emerging. 
