THE STATE ENTOMOLOGIST. 89 



THE TILE-HORNED PRIONUS— Prionus imbricornis, Linn. 

 (Coleoptera Prionidae.) 



There is another species, the Tile-horned Prionus (Prionus imbri- 

 '- Fis * G3 '-' ~*s*_ cornis, Linn., Fig. 63 c?) — so called from 



the joints of the male antennae lapping 

 Jover one another like the tiles or shing- 

 les of a roof— which very closely re- 

 sembles the Broad-necked Prionus, and 

 is with us much commoner. It may be 

 distinguished at once from this last by 

 the antennas of the male being about 

 19-jointed, and those of the female about 

 16-jointed;* whereas both sexes of the 

 Broad-necked Prionus have 12-jointed 

 antennae. In other respects, these two 

 ~<f beetles are almost exactly alike, so that, 



if the antennas happen to be broken, it is not very easy to tell one 

 from another. 



Hitherto it has not been known upon what kind of tree this spe- 

 cies fed, but I was fortunate enough last summer to ascertain that it 

 also infests grape-roots. On the first of July last, Mr. Isidor Bush, of 

 Bushburg, brought me quite a number of full-grown larvae which he 

 had taken from the roots of his grape vines. These were so very sim- 

 ilar in appearance to those which produced the Broad-necked species, 

 that I had not a suspicion they would produce anything else, and I 

 was consequently greatly surprised when I bred from them a number 

 of the Tile-horned species under consideration. By collecting to- 

 gether fibres and chips of the roots, they form a loose sort of cocoon, 

 and transform, either inside or outside of the root, to pupae, which re- 

 semble so closely that shown in Figure 62, that they can scarcely be 

 distinguished from it. 



We have, therefore, two distinct insects which bore into the roots 

 of the Grape-vine, and which, though distinct, are so closely allied, 

 that the females can only be distinguished by the number of joints in 

 their antennae. One of these is known to attack, besides the Grape, 

 the Apple, the Lombardy poplar and the Balm of Gilead, and the 

 other is very likely equally indifferent as to its choice of diet. 



The accounts given in my former article, of the immense borers 

 found in Osage Orange roots, and even in the roots of corn-stalks, un- 

 doubtedly refer to one or the other of these insects, and probably to 

 the Tile-horned species, as that is the most common. 



* Having examined nearly 20 males of this species, I have found the antennal joints to vary 

 in number from IS to 20, the same specimen often having a different number of joints in the right 

 and left antenna. In one $ the antennas are both of them 16-jointed, in another £ they are both 

 of them 17-jointed. The typical number of joints in the Coleopterous antenna is only 11 ; and the 

 number being so variable in these many-jointed antennae is in accordance with the general rule, 

 hat multiple parts are often variable. 



