THE DAVEY INSTITUTE OF TREE SURGERY 
weakening the limbs so that they are easily broken by a storm or 
fall of their own weight. 
41. Control. From what has been said, it is evident that the 
control of this pest is a difficult matter, especially upon large 
trees. A close inspection of the upper limbs cannot be made to 
locate or kill the larve within their burrow, or to remove the af- 
fected limbs and destroy them with the contained larve before the 
injury is too great. 
42. All that can be recommended is to dig out the larve, or 
destroy them with a wire or by injecting carbon bisulphide into 
their burrows. Infested limbs that fall or are pruned off should 
be destroyed before the larve desert their burrows. Repellants 
may help to check egg laying, but the whole of the trunk and larger 
limbs will have to be protected from May until September to be 
successful. The moths can also be collected by trap lights or by 
hand and killed. Protecting the native birds that feed upon these 
insects is also a powerful means of fighting them. 
43. It has been generally observed that healthy, vigorous 
trees, while they are not free from attack, are not as badly injured 
as the unhealthy ones. Moreover, they outgrow the effect of the 
injury much quicker. 
2. CARPENTER WORM 
Family COSSID/A. Species Prionoxystus robine Peck 
44. This moth is a native of this country, but belongs to the 
same family as the leopard moth, and has similar habits. The 
larve are similar in appearance, but this one grows to be fully 
three inches long, and confines its work more to the trunk and the 
heart-wood. 
45. The carpenter worm was first described by Peck as Cossus 
robing, but Newman changed the genus to Xyleutes, and later it 
was changed to Prionoxystus,—the name by which it is now known. 
It has also received the following specific names: plagiotus Walker, 
crepera Grote, reticulatus Lintner, and zabolicus Strecker. 
46. Food Plants. It feeds upon black locust, black, red and 
white oak, ash, maple, cottonwood, poplar, willow, and chestnut. 
47. Symptoms. Large, half-inch galleries in the trunk and 
larger limbs, running parallel with the grain and of about the 
same size throughout their length, are generally the work of this 
Page 9 
