32 TRANSACTIONS OF THE ILLINOIS 



affords. And, first, 1 may state that cultivation of the soil is beneficial 

 as a means of keeping down injurious insects ; that is, as a general rule, 

 the result is more favorable in this respect under cultivation, than where 

 the soil is left wholly uncultivated ; and I believe this accords with the 

 conclusion drawn from experience on the plant side of the question. The 

 next point, and one of some importance is, should a crop of any kind be 

 raised, and if so, what should be its character? Looking at the subject 

 from an entomological standpoint only, I am rather inclined to think 

 that, as a general rule, the answer would be that it would be best without 

 any, especially after the trees come into bearing. But looking at the 

 matter from the side of economy, I suppose it will have to be conceded 

 that while the orchard is young the value of the crops will exceed the 

 difference between the results of the two methods, and hence it is best to 

 have something in cultivation. 



But grass should never be grown, as it affords food not only for 

 larvae, which may injure the young and tender roots of the trees, as the 

 wire-worms (elateridce) and grubs, etc., but also for those which may 

 come forth in the perfect state, as the various May-beetles, to destroy the 

 foliage ; it also affords shelter and a hiding place for many others more 

 or less injurious to the trees ai"Kl fruits, especially those which appear early 

 in the spring, or remain late in the fall after the leaves have fallen. I am 

 inclined to believe, though I have not investigated this point carefully, 

 that the predaceous ground-beetles, which are such excellent auxiliaries 

 in this warfare, are less apt to accumulate where grass is growing than 

 where it is not. I might also add that the Tettigonians, or leaf-hoppers, 

 are more abundant where grass is than where it is not, and although the 

 species generally confine their attacks to a particular group or even species 

 of plants, yet in dry seasons their operations, in a limited degree, may be 

 transferred to the leaves of the trees, which are ill able to bear it at such 

 times. The grass, if heavy, is likely to draw nourishment from the soil 

 to the detriment of the trees, thus weakening them, and rendering them 

 more liable to the attacks of the flat-headed borers, or Buprestians, which, 

 as a rule, attack in preference those trees which are injured, sickly, or in 

 some way weakened in their growth ; and nature has given them such a 

 delicate instinct that they can often ascertain this before the orchardist 

 has perceived it. 



For similar reasons, though not applicable to the same degree, I 

 think wheat, oat and barley crops should be avoided, at least winter 

 wheat. 1 will mention here one case bearing upon this point, which was 

 recently brought to my notice : 



About a month ago I received from Efifingham county some cater- 

 pillars, which were doing considerable damage to wheat at one point. 

 They were evidently the larvae of an acronyctian, either very closely 

 allied to, or identical with A. oblinita of Smith & Abbott, a moth which 

 Prof. Riley, or some one else, has named the Smeared Dagger. The 

 larva of this species is a very general feeder, attacking not only the Poly- 

 ganian or knot-weed, which it appears to prefer, but also wheat and the 

 leaves of fruit trees, and according to Prof. Riley, especially the peach. 



