STATE AGRICULTURAL SOCIETY. 
835 
JOINT-WORM FLY. LARVA FROM WHICH IT COMF.S. 
such perfect knowledge of it as would settle the point definitely 
and conclusively; and for a time I had it in serious contempla¬ 
tion to visit Virginia on this business. But other avocations 
came to me, which diverted me from this purpose. 
Was any further light upon this topic attainable ? How was 
it possible for this Eurytoma to thus come from these joint-worms 
and the worms in barley in every observed instance, to the 
amount of some hundreds, if it were not the legitimate descend¬ 
ant of those worms. It occurred to Dr. Harris that a portion 
of the joint-worms might perhaps complete their transformations 
and come from the straw the first summer, leaving only those 
containing parasites to pass over till the following spring, and 
lie addressed Mr. Ruffin on this subject, desiring him to have 
this point examined. Prof. Cabell, the only respondent to this 
inquiry, states that lie has known a few flies to leave the straw 
the first year, but in each instance the fly which came forth thus 
was the same Eurytoma. It, moreover, is quite evident that no 
considerable number of flies do leave the straw anterior to the 
hatching of the Eurytoma in May, or we should meet with their 
evacuated cells, with the openings therein through which the 
inmate had made its exit. 
Another important inquiry suggested itself to Prof. Cabell. 
Although the larvae of the gall-flies ( Cecidomyia ) of the order 
Diptera, and of the gall-bees ( Cynips ) of the order Hymonoptera, 
may be closely similar to each other, is there not some character 
by which they can be distinguished, whereby it can be ascertained 
whether this joint-worm itself is really a Dipterous larva, as I 
had confidently pronounced it to be, or a Hymenopterous larva 
as it must be to produce this Eurytoma? Upon comparing the 
Dipterous larvm of the Hessian fly with the Hymenopterous larvao 
found in oak-galls, Prof. Cabell noticed that the blackish jaws of 
the latter were placed upon a straight transverse lino, whilst in 
the former they have an oblique direction, their ends meeting 
at an acute angle. Thereupon inspecting the joint-worm he 
found its jaws plainly indicated it to be a Hymenopterous larva. 
Specimens were forwarded to Dr. Harris, which were carefully 
examined by him, and also by Prof. Jeffries Wyman, a skilful ana¬ 
tomist and experienced microscopical observer. They fully 
confirmed the correctness of Prof. Cabell. 
