HYMENOPTERA. 445 



abundance, those of the foregoing Eurytoma. Tlie other larva;, 

 few in number compared with the joint-worms, are distin- 

 guished therefrom by their inferior size, and whiter color, and 

 by being sparingly covered with short hairs. Their heads are 

 round, are provided with blackish hooked jaws, and have two 

 little tubercles on the front. I judge them to be the young of 

 one of the parasites, probably of the Torymus, described on a 

 former page. 



The foregoing account might be thought to afford conclu- 

 sive evidence that the Evrytoma alone was the author of the 

 mischief done to the wheat and barley, and that it is not a 

 parasitical insect. In favor of this conclusion, we have the 

 fact that hitherto no person has succeeded in obtaining from 

 the diseased wheat-straw so much as a single specimen of 

 Cecidoinyia; while both the wheat and the barley straw have 

 yielded to several observers, in repeated instances, numerous 

 specimens of the same kind of Eurytoma,^ and nothing else, 

 saving an extremely small number of lesser parasites. The 

 determination of this difficult and interesting question is of 

 much importance in a scientific and an economical point of 

 view. The great amount of property that is at stake, and the 

 serious losses already sustained by the ravages of the joint- 

 worm, render it necessary to ascertain the true history of the 

 insect before proceeding to take measures for the protection of 

 our crops. We are to consider, in destroying the Enn/toma^ 

 whether we shall kill an enemy or a friend. If it be a para- 

 site, as the almost universal opinion of entomologists would 

 lead us to believe, it would be the height of folly to attempt 

 to interfere with its operations. On the other hand, if we can 

 show it to be a plant-eating insect, we may use such means 

 as are in our power towards checking its career, not only with 

 perfect safety, but with eminent advantage. In this case, in 

 dealing with the joint-worm, we need not be restrained by the 

 consideration that the diseased straw contains also some truly 

 parasitical larva? ; for these, as already stated, are very few in 

 number compared with the immense swarms of the Eurytoma 

 that are annually produced. If we can succeed in extermi- 

 nating these destroyers, we shall have no occasion for the 

 services of the parasites. 



