THE WHEAT CROP. 79 



but whose presence there naturally leads a farmer to 

 connect them with some of those injuries which his crops 

 sustain, and for which he can assign no distinct cause. 

 Many of these, no doubt, like those already described, are 

 directly injurious to our crops; while again, many of 

 them are placed there for the purpose of controlling the 

 ravages of those injurious to us. Considering their num- 

 bers, and the vast bearing they have upon the general 

 welfare of a country, it surely is our interest to pay more 

 attention to them than we have hitherto done to seek 

 to know the nature and habits of those which are injurious 

 to our crops, so that we may do our best to prevent their 

 ravages, and also how to distinguish them from those 

 friendly insects, which so materially limit their powers, 

 and which it should be our duty, as it is our interest, to 

 protect and encourage. 



Amongst those we see infesting wheat we find the 

 wheat -plant louse, the Aphis cerealium, a fat, pale, 

 green coloured insect, with longish dark coloured horns, 

 frequently very abundant in the ear immediately before 

 harvest time. It is said to suck the stem, and thus im- 

 poverish the grain. Whatever damage it may be capable 

 of doing and but little is known about it is materially 

 lessened no doubt by the check placed upon it by the 

 presence of a parasitic fly, the Aphidius Avence, which 

 destroys it by puncturing its body, and depositing eggs 

 in it. 



The Corn-bugs, Miris Tritici and M. erraticus, are 

 very common in the wheat plant from the time it appears 

 in ear. Here again our knowledge is sadly defective. 

 Curtis tells us they have a proboscis for sucking, bent 

 under the breast, but it is not known whether this is for 

 piercing and sucking the grain or the bodies of other 

 insects. It is not improbable that in their larva and pupa 

 states they are carnivorous, and in their perfect state 



