356 ILLINOIS STATE HORTICULTURAL SOCIETY, 



Prionides are large, broad, somewhat flattened, and largest in front ; one 

 of them, the larva of the broad-necked prionus {Frionus laticoUis), which 

 infests grape and apple roots, when fully grown, is nearly three inches 

 long ; the legs are very minute. 



The larvte of the sub-family Cerajnhycides resemble those of the 

 Prionides, in having six legs, but the body is more cylindrical, the incisions 

 between the segments are more deeply impressed, and they are usually 

 smaller, so far as Illinois species are concerned. They work in the trunks 

 of various trees, or in twigs — the locust-tree hoxer {Clyttis robinice), the 

 ash-tree borer {Neoclytus caprcsa), and the honey-locust borer {F,bitria 

 quad rige])iinata) being familiar examples of the trunk-bgrers of this sub- 

 family, and oak-twig pruner or borer {Elaphidion parallelume) of those 

 which inhabit the twigs or small branches of trees. 



This hasty sketch will give you an idea of a method of grouping 

 borers by their larval characters, which will assist you very greatly in 

 arriving at a correct idea of the perfect state of any wood-borer larva 

 with which you may meet which is new to you. In order to make it as 

 brief as possible, I present it here in the form of a synoptical table : 



WOOD-BORING LARV./E. 



A. Possessing legs or feet. 



B. Having more than six feet; usually sixteen. 



c. Large size, true caterpillar, cylindrical ; boring into the wood of the trunk ; 



perfect insect a large moth. (Ex. locust-boring caterpillar.) — Xylentes. 

 cc. Small, usually somewhat flattened beneath; boring into the roots of trees, 



stems and canes of shrubs, or mining under bark ; perfect insect a 



moth with partially transparent wings. (Ex. peach-root borer.) — 



^■Egeriadce. 



BB. Having but six legs. 



d. Tail terminating in a horny spine or point ; boring into the trunk; perfect 



insect wasp-like. (Ex. the pigeon tremex.) — Uroceridce. 

 dd. Tail without a spine. 



e. Large size, somewhat flattened, largest in front, and tapering backwards; 



infesting the roots of grape-vines and trees; perfect insect a large, 

 brown, flattened beetle. (Ex. broad-necked prionus.) — Prionides. 

 ee. Illinois species, medium size to small; cylindrical, sometimes enlarged in 

 front, sometimes nearly equal in size throughout ; incisions distinct ; 

 bore into the wood of the trunk, some into twigs; perfect insect a long- 

 horned beetle, with the head not vertical. (Exs. locust-tree borer and 

 oak-twig pruner. ) — Cerambycidcs. 



AA. Footless grubs. 

 C. Of various sizes, from medium to minute ; front segments usually more or less 

 enlarged ; never enlarged in the middle so as to taper toward each 

 extremity, nor curved. 



