Insect Destruction of Fire-Killed Timber. 365 



borers, — the Cerambycid and Buprestid beetles, — whose larvae 

 make large burrows deep into the wood. 



The destructive "Sawyer" (Monohammus titillator) of the 

 Southern States seem not to be present in the Black Hills. The 

 chief damage is done by the larva of a Buprestid beetle, probably 

 the Heartwood Pine Borer (Chalcophora virginiensis) or one of 

 its western forms oregonensis, or angulicollis montana. The 

 three forms mentioned do not differ materially. All are large 

 metallic lustered, bronze colored beetles, about an inch long and 

 a quarter of an inch wide. They fly with a distinct buzzing 

 sound. 



The larvae are elongated, whitish, flatheaded, legless grubs. 

 The head is yellowish to brownish, and armed with strong jaws, 

 which can be heard as it excavates in its burrow. The length 

 at maturity is an inch and a half or more. 



The adults fly in July, during the third week of that month the 

 woods are full of them, but by the end of the first week in August 

 all seem to have disappeared. The flying season probably lasts 

 from the middle of June to the last of August at the outside. 



The eggs are layed in holes cut in the bark by the female, oc- 

 casionally in living, more often on recently dead trees. They 

 hatch in a few days, and for a few weeks bore in the bark- Un- 

 der favorable circumstances they may enter the wood within a 

 month; by the end of two months, if conditions are favorable, 

 they may have bored into it for two inches. The larval stage 

 lasts till the following season, and may last for two years. Their 

 activity does not continue after cold weather sets in, and the 

 wood freezes. 



Character of Insect Damage. Ambrosia beetles aid in bluing 

 fire-killed timber, but it is seldom that the sapwood escapes 

 bluing even without their assistance. If timber is cut before it 

 is badly infested by the larger borers, the work of the ambrosia 

 beetles is usually removed with the slabs. 



The larger borers if abundant will in time completely riddle a 

 log, so that it is worthless save as firewood. In a single season 

 they may reduce its value from thirty to fifty per cent. 



Effect of the Season of the Fire. The severity of attack by 

 boring insects varies with the season of the fire. It can of course 

 take place immediately after one only during the season when the 



