350 YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 



are present in the same piece of wood, the solid wood is often literally 

 honeycombed with their mines (fig. 23). Pupation takes place in the 

 wood and the adult beetle usually emerges in May or June of the 

 year following that in which the egg is laid. 



It has been found that hickory cut between August 10 and No- 

 vember 1 usually is not damaged by this borer. Therefore, where 

 much damage occurs from this source, all cutting of green timber 

 should be done as nearly as possible within this period. If it is 

 absolutely necessary to do the cutting in the spring or early sum- 

 mer, the bark should be removed and the tops and useless branches 

 burned. 



THE BLACK-HORNED PINE-BORER. 



(Callidium antennatum Newm. ) 



Injuries by the black-horned pine-borer to the bark or sapwood of 

 dead or dying cedar, juniper, pine, and spruce are common generally 

 over the United States. Often the timbers in rustic houses are found 

 to be infested, and rustic work is especially liable to injury, since the 

 presence of bark is absolutely necessary for the early development of 

 the borer. 



When first hatched from the egg the larva feeds exclusively on the 

 inner bark, making an irregular winding mine. Later it also grooves 

 the surface of the wood (PI. XXIII) in making its mine, thus com- 

 pletely separating the bark from the wood, causing it to become loose 

 and, in many cases, to fall off. As the essential part of rustic work 

 is the bark, this sort of injury to it is quite a serious matter. The 

 larva is an elongate, fleshy, yellowish-white grub, usually about a 

 half inch in length when full grown. After working in the bark 

 until a certain period of development is reached, the larvae enter the 

 wood and continue their mines there. Usually they do not go deeper 

 than the sapwood, except in small stems or branches, where they 

 may penetrate the heartwood. The larva pupates in the wood. The 

 adult which finally emerges is a medium-sized, robust beetle, 9 to 14 

 mm. in length, blue to green in color throughout. There appears to 

 be but one generation a year. Adults fly and deposit eggs during 

 the months of April, May, June, and July. The winter is prob- 

 ably passed in the larval stage, the adults emerging the following 

 spring. 



As a preventive against injuries by this borer, cedar, juniper, pine, 

 and spruce should be cut in the late summer, fall, or early winter. 

 If cut during the period between January and August, the trees 

 should be barked when felled. In the case of rustic work already in 

 use when found to be infested, some relief may be secured by inject- 

 ing bisulphid of carbon into holes in the bark through which sawdust- 



