194 PROTECTION OF WOODLANDS. 



The generation of the cervicorn beetles varies, being simple or 

 annual in many species, biennial with most of them, and mult- 

 annual in some cases. The imago bores its way out to the 

 surface by an oblique passage having an elliptical exit-hole. 



The larvae of the cervicorn beetles live chiefly in the wood of 

 broad-leaved species of trees, and, as sickly or unsound stems are 

 for the most part attacked, the actual damage they do is on that 

 account comparatively slight ; but at the same time they are not 

 infrequently found on sound stems, which become riddled with 

 holes by the larvae, and are thus rendered of less technical 

 value than they would otherwise possess. 



Annihilative or exterminative measures are hardly ever neces- 

 sary on any extensive scale, nor could they easily find practical 

 application. The following comprise the chief species : 



The large Oak Cervicorn, Cerambyx heros (ITammaticherus 

 This beetle is about 1/6 to 2 inches in length. The yellowist 

 white larva, extending to about 2 '8 inches when full grown, is 

 distinguished by having large elliptical horny plates on the upper 

 portion of the different segments. It inhabits old Oaks, occur- 

 ring frequently in the sound wood, which is of course greatly 

 damaged for technical purposes by the larval borings ; these are 

 about as thick as a finger. Its generation is biennial. 



The large Poplar Cervicorn, Cerambyx (Saperdas) carcharias 

 (vide Plate I. fig. 11). This is a yellowish-brown beetle, with 

 black-spotted thorax and elytra. The round, footless, yellowish- 

 white larva attains a length of 1/4 inches ; it has bro) 

 mandibles and scales from the third to the tenth segment, 

 generation is biennial, and as larva it feeds chiefly in Poplars 

 Willows up to about their 20th year. 



The Aspen Cervicorn, Cerambyx (Saperda) populnca. 

 beetle is only 04 to 0'52 inches in length, and black in colour, wit 

 yellow hairs ; the feelers are alternately ringed with blue and 

 black. The yellow larva, which lives chiefly in Aspen seedlings 

 or stoles of from 2 to 6 years of age, at first feeds in the outer 

 layers of sapwood, but during the second year bores its way into the 

 pith, and produces knots and swellings that are often conspicuous 

 on the slender stems. 



Its generation is also biennial. In order to exterminate 

 insect, damaged stems should be cut back and burned, and 

 beetles should be collected when swarming during June. 



