28 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 
primary but are probably secondary, are reared from the bags. Three 
of these are Ichneumonids, viz: (1) Pimpla conquisitor Say (Fig. 11); (2) 
Pimpla inquisitor Say, and (3) Hemiteles thyridopterigis Riley (Fig. 12). 
Fic. 12.—Hemiteles thyridopterigis: a, male; b, female; 
c, sack of bag-worm cut open, showing cocoons of parasite, 
natural size. 
Of these, the last-named is most abundantly bredyand we have always 
considered it as the most important parasite of the Bag-worm. ‘he 
past season, however, we have ascertained that three species of the 
genus Hemiteles, viz: H. utilis, and two undescribed species, are un- 
questionably secondary parasites, and this renders it quite likely that 
H. thyridopterigis may also be secondary, or, in other words, a parasite 
of one of the true parasites of the Bag-worm. It is a question, how. 
ever, which only the most careful study, with abundant material, can 
decide, as the law of unity of habit in the same genus finds many excep- 
tions in insect life. The other parasites are as follows: (4) Chalcis ovata 
Say. This parasite is a very general feeder on Lepidopterous larvee, and 
we have bred it from seven widely different species. (5) Spilochaleis 
maric (Riley). This species, while parasitic on Thyridopteryx, is more 
partial to the large silk-spinning caterpillars, as we have reared it from 
the cocoons of all of our large native Silk-worms. (6) Pteromalus sp. 
This undescribed Chalcid is found very abundantly in the Bags, but 
may be a secondary parasite. (7) Dinocarsis thyridopterygis AShmead.* 
This parasite was bred from the Bags in Florida by Mr. William H- 
Ashmead, who believes it to be parasitic on the eggs. (8) Tachina sp, 
We have bred a large bluish Tachinid from the Bags. Its eggs are 
commonly attached to the Bags externally, near the neck, and the 
young larve, on hatching, work their way into the case. They fre- 
quently fail, however, to reach the Bag-worm. 
*Mr. Ashmead’s description (Canadian Entomologist, XVIII, No. 5, p. 97, May, 
(1886), shows that this species cannot belong to Dinocarsis, as limited by Mayr. 
