2i6 THE CANADIAN ENTOMOLOGIST. 



20th, 1894) a Cerambycid larva, that was found to be exceedingly de- 

 structive to the heartwood of large tulip trees, as mentioned in a former 

 paper (Insect Life, Vol. VIL, p. 150). Subsequent observations lead me 

 to conclude that this is one of the most destructive wood-boring insects 

 that infests the wood of living trees, and that the destruction of valuable 

 timber by it results largely from primary injuries by fire. 



The cocoons of a parasite ( Gynuiosetis americainis, C.) were found 

 in larval mines, evidently of this species, in the same tulip log previously 

 mentioned, which may be of some service in keeping this pest in check. 

 It evidently attacks the larvae at the time they are forming the exit gallery 

 for the adult, since at other times the larvaj are so deep in the heartwood 

 of the tree that they could not be reached by the ovipositor of the 

 parasite. 



On July 7th of the present year (1896), I found a female example of 

 the large and beautiful Lepiura emarginata ovipositing in the dead wood 

 of a wound in a living beech tree, and numerous large holes were ob- 

 served in the same wood, from which the beetles had evidently emerged, 

 thus indicating that this species may also be classed among the destruc- 

 tive heartwood borers. 



There are probably several other Cerambycid and Buprestid species 

 that contribute to this class of injury to living trees, and, since the results 

 of their work are practically the same, they may be designated as 

 Destructive Heartwood Borers. 



Destructive Bark Borers. 



With the exception of certain Scolytidse, notably Dendroctonus 

 frontalis., the most destructive and dangerous class of insects that attack 

 living trees belongs to the genus Agrilus, since their habit of ovipositing 

 in the bark of healthy trees in which it is possible for the larvse to develop 

 makes it possible for them to effect a terrible destruction of timber 

 should they ever occur in sufficient numbers to take the character of an 

 invasion. 



Agrilus bilitieatus is already to blame, either directly or indirectly, 

 for the death of a great quantity of oak and chestnut timber, not alone in 

 West Virginia, but in different sections of the country between here and 

 the Mississippi River. Until last fall the dying of trees with which this 

 insect was intimately associated was decidedly on the increase. 



