INSECTS AFFECTING VEGETATION 



trunks are sometimes 1.5 inches in diameter one way by 0.75 inch 

 the other, thus causing serious damage to the wood. These, with 

 other large wood-boring beetle larvae, sometimes infest the top part 

 of the trunk and the larger branches of oak trees, where their contin- 

 ued work results first in the dead and so-called staghorn top and 

 subsequently in broken, decayed and worthless trunks. 



Ambrosia Beetles. One of the commonest defects in white oak, 

 rock oak, beech, whitewood or yellow poplar, elm, etc., is that known 

 to the lumber trade as grease spots, patch worm, and black holes. 

 This defect is caused by one of the timber beetles or ambrosia bee- 

 tles, which makes successive attacks in the living healthy sapwood 

 from the time the trees are 20 or 30 years old until they reach the 

 maximum age. Thus the black-hole and stained-wood defect is scat- 

 tered all through the wood of the best part of the trunks of the trees. 

 The average reduction in value of otherwise best-grade lumber 

 amounts, in many localities, to from 25 to 75 per cent. The defect 

 is commonly found in oak and elm furniture and in interior hard- 

 wood finish in dwellings and other buildings. 



The Locust Borer. The locust, as is well known, suffers to such 

 an extent from the ravages of the locust borer that in many locali- 

 ties the trees are rendered worthless for commercial purposes or they 

 are reduced in value below the point of profitable growth as a forest 

 tree, otherwise this would be one of the most profitable trees in the 

 natural forest or artificial plantation and would contribute greatly 

 to an increased timber supply. 



Turpentine Beetles and Turpentine Borers. While the soft- 

 wood trees, or conifers, suffer far less than the hardwoods from the 

 class of enemies which cause defects in the living timber there are a 

 few notable examples of serious damage. There is a common trouble 

 affecting the various species of pine throughout the country known 

 as basal wounds or basal fire wounds. It has been found that a large 

 percentage of this injury to the pine in the States north and west of 

 the Gulf States and in the Middle and South Atlantic States is 

 caused by the red turpentine beetle and in the Southern States by 

 the black turpentine beetle. These beetles attack the healthy living 

 bark at and toward the base of the trunks of medium to large trees 

 and kill areas varying in size from 1 to 10 square feet. These dead 

 areas are subsequently burned off by surface fires and are then gen- 

 erally referred to as fire-wounds. The further damage to the ex- 

 posed wood by successive fires, decay, and insects often results in a 

 total loss of the best portion of the tree, or a reduction in value of 

 the lower section of the trunk of from 10 to 50 per cent. These and 

 similar wounds in the bark of trees, including those caused by light- 

 ning and by the uncovering and exposure of the wood in turpentin- 

 ing, offer favorable conditions for the attack of the turpentine borer, 

 the work of which, together with that of two or three others with 

 similar habits, is very extensive, and causes losses amounting to from 

 10 to 50 per cent of the value of the wood of the best part of the trees 

 thus affected. 



