560 HYMENOPTERA. 



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 be- 

 fore proceeding to take measures for the protection of our 

 crops. We are to consider, in destroying the Eurytoma, 

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

 parasite, 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 larvae; 

 for these, as already stated, are very few in number com- 

 pared with the immense swarms of the Eurytoma that are 

 annually produced. If we can succeed in exterminating 

 these destroyers, we shall have no occasion for the services 

 of the parasites. 



Admitting the Eurytoma to be the sole cause of the 

 mischief, the following suggestions will be found useful in 

 arresting its ravages. As the disease is seated mostly near 

 the base of the straw, in or near the second or the third 

 joint, the greater part of the diseased portions will be left in 

 the stubble when the grain is reaped. Most of the insects 

 remain unchanged in the stubble till the following year. * If, 

 then, we can destroy the maggots in the stubble before they 

 have acquired wings and made their escape, we shall, in great 

 measure, restrain their further propagation and increase ; for 

 it is in the winged state alone that insects propagate their 

 kind. It has been found in Massachusetts that ploughing in 

 the stubble has little or no effect upon the insects, which con- 

 tinue alive and uninjured under the slight covering of earth, 

 and easily make their way to the surface when they have 

 completed their transformations. 



