90 SECOND ANNUAL REPORT OF 



Several persons who have recognized this immense borer from 

 the figure and description which I published last year, have informed 

 me that they have found it on prairie land, and Mr. Wm. 0. Holmes, 

 nurseryman, of Plattsburg, writes: "The Borer described on page 124 

 of your Report is destroying a good many of our apple grafts, set last 

 spring. The root not being large enough for them to work inside, 

 they eat out about one-third of the bark, and hollow out the rest of 

 the root. Our nursery is on prairie, broke in the fall of 1867 and spring 

 of 1868." Now the fact of these large root-feeding borers occurring 

 in such numbers in recently turned-up prairie land where no large 

 roots exist, would have been perfectly inexplicable had I not been 

 cognizant of other facts which threw light on the subject. 



There is a small dimorphous male form of the Tile-horned Prionus 

 not more than half the normal size, and of a much paler yellowish 

 color, which is quite common in the West, and which I have found 

 even more common around St. Louis, than the true type. I know 

 that this form is often found in prairie regions, and my entomological 

 friend Chas. Sonne, of Chicago, Illinois, informs me that a relation of 

 his, Mr. F. Jaeger, of Siegel, Illinois, in digging a cellar, once found 

 immense numbers of these large grubs near the surface of the ground. 

 A whole lot of them were sent to Mr. Sonne, and he bred from them 

 numerous specimens of this small form of the Tile-horned Prionus, 

 every one of them males, and every one with nineteen joints to the 

 antennas. On another occasion, at the same place, Mr. Sonne, having 

 placed a lamp on a grind-stone, found that these beetles swarmed 

 around the light, and next day upon examining a number which he 

 captured, they all proved to be, in like manner, the small yellow 

 form, and all males. Now, Mr. Jaeger's house is remote from any 

 timber whatever, there being but a few scrub willows here and there 

 near by ; and, from these facts, and those mentioned by Mr. Holmes, 

 we are forced to the belief that these grubs (at least those of the 

 small c? dimorphous form) are able, not only to subsist on the roots 

 of small shrubs and very young trees, but also upon those of herba- 

 ceous plants. Mr. H. A. Mungor, of Lone Cedar, Martin county, Min- 

 nesota, has had a similar experience ; for he often ploughs up these 

 grubs in prairie land, and has captured the beetles a full mile away 

 from any trees or shrubs, except a few specimens of a suffruticose 

 plant known as the Lead-plant (Amorpha Canescens), which very 

 seldom grows a root there, of over one-half inch diameter. He has 

 also actually bred the beetle frompupre found in such prairie ground. 

 Therefore, some of the accounts — such as their occurring full grown 

 in the roots, of annuals like corn and cabbage, and in those of grape- 

 vines but one year planted — which were not easily explained before ; 

 become perfectly clear, now that we have a better understanding of 

 the facts in the case. 



Now then comes the point of practical importance. It may with 

 reason be argued, that it matters little to the Grape-grower to which 



