INSECT ENEMIES OF WESTERN FORESTS ]^59 



Gheilosia {H). This type of defect is very prevalent in western 

 hemlock growing in western Washington and Oregon at elevations 

 below 1,800 feet and is called the "black check" of hemlock. Tliese 

 defects do not impair the wood for structural purposes but render 

 a high percentage worthless for finishing wood, staves, or other 

 special purposes. 



The adults are small two-winged flies which lay their eggs on the 

 bark of the trees, probably on the resin which exudes from feeding 

 punctures made by the hemlock hylesinus. The maggots enter the 

 bark, making a small wound, and feed on the sap and inner bark. 

 The larvae Avhen full grown are white maggots three-fourths of an 

 inch in length, wdth the fore part of the body thickened and with a 

 long, telescopic, protractile tail. Feeding continues for several years, 

 then in the spring puparia are formed in the resin mass at the en- 

 trance to the wound, and the adult flies emerge in April and May. 



Two species have been recognized as important in the West. 

 Oheilosia alaskensis Hunter makes the black check in western hem- 

 lock (fig. 79) and is distributed from Oregon to Alaska. C. hoodi- 

 ana Bigot does similar work in white and lowland fir in the same 

 region and also has been reported from New Mexico. There are 

 several other species whose habits are not fully known, which cause 

 similar wounds in other western conifers. 



INSECTS WORKING IN SEASONED OR DECAYING WOOD 



POWDER-POST BEETLES 



A group of beetles belonging to the families Ptinidae, Anobiidae, 

 Bostrichidae, and Lycticlae are called powder-post beetles because 

 the larvae burrow into hard, dry wood and reduce it to fine powder. 

 There are hundreds of species in this group, many of which confine 

 their attack to deadwood in the forest and are of little economic 

 importance. Most of this group confine their attacks to the sapwood 

 of the hardwoods, but a few species attack pine and Douglas fir and 

 occasionally do some damage. A few work in finished products and 

 are extremely destructive on account of their ability to reinf est wood 

 repeatedly until it is completely destroyed and to attack any 

 exposed surfaces of furniture, flooring, and sills, and thus establish 

 themselves in utilized wood products. 



Great care needs to be taken in storage yards to prevent infestation 

 from developing before the sapwood of hardwoods is treated with a 

 filler, painted, or varnished and thus protected. Badly infested 

 stocks of tool handles, oars, or building material should be burned. 

 If lightly infested they can be treated by soaking in kerosene or b}^ 

 applying liberal doses of crude liquid orthodichlorobenzene. 



The Lyctus beetles (^, 74) are probably the most dangerous and 

 destructive members of this group (fig. 80). The adults are small, 

 flat, slender, dark-brown beetles about one-eighth to three-sixteenths 

 of an inch long. Eggs are laid in the pores of the wood, and the 

 larvae bore only in the sapwood of various hardwoods, reducing it to 

 a flourlike powder. The insects pass the winter as larvae. Pupa- 

 tion occurs in the spring, and the new adults appear early in the 

 summer. In heated buildings development is hastened, and under 

 such conditions adults may appear much earlier. Small round holes 



