26 Annals Entomological Society of America _[Vol. VII, 
From this he concludes that the cells of the Malpighian 
vessels are doubled in size while those of the oenocytes increase 
threefold. 
Now in comparing Table II and Table III, it will be seen 
that in Dryophanta erinacei there is no indication of any cor- 
relation existing between the oenocytes and the Malpighian 
vessels. The oenocytes have reached their maximum when the 
larva is in the prepupal stage, and the Malpighian vessels are 
largest when the larva measures 124mm.—approximately the 
middle of August. As far as our investigation has gone we have 
found nothing to support the idea of any correlation in the 
development of the oenocytes and the Malpighian vessels. 
CONCLUSION. 
The conclusions drawn from the foregoing study of Dryo- 
phanta erinacei are as follows: ‘ 
1. From a study of the life-history of Dryophanta erinacei 
we have another illustration of dimorphism in the Cynipide. 
A. The agamic form of Dryophanta erinacei produces the 
oak hedgehog gall on the veins of the white oak leaves, passes 
through five larval stages extending over a period from the last 
of June to the first of September. Pupation occurs on the first 
week in September, and the adults emerge about the fifth of 
November. 
B. The adults oviposit on the leaf and flower buds of the 
same tree. 
C. The following spring the eggs hatch, and the larvae 
produce galls on the leaf scale or the terminal growing points 
of the buds, from which within two weeks the sexual form of 
Dryophanta erinacei emerges. 
D. These oviposit on the midrib and lateral veins of the 
young leaves of the white oak. From the eggs deposited 
emerge the young larve which produce the summer gall. 
E. The sexual form belongs to the genus Dryophanta, and 
will therefore be known as the sexual form of Dryophanta 
erinacei, of which the insect, formerly known as Acraspis 
erinacei is the agamic form. 
2. The study of the parasitic and guest life shows that the 
following insects inhabit the gall: Decatoma flava (Ashmead) ; 
Decatoma querci-lana-dorsalis (Fitch); Decatoma varians 
