266 



Washington and Oregon. Loss from the attacks of this beetle can be 

 avoided by cutting unhealthy timber as soon as noticed and removing 

 all felled timber as rapidly as possible. 



There are many undescribed species of the genus Xylehorus, several 

 of which are wingless and remain throughout their lives in the galleries 

 where they develop. The only member of this genus attacking 

 Douglas fir is X. xylographus, Say {saxeseni. Ratz.). The fertilised 

 females pass the winter in the brood chamber, emerging in early 

 spring to attack weak, dying or felled trees. An entrance is made 

 through the bark into the sap wood, which leads to a brood chamber 

 parallel to the grain of the wood ; this may be in the sapwood or deep 

 in the heartwood. Attacks are made for preference at the edge of 

 wounds or other insect burrows, or in deep crevices. Several females 

 frequently work at one gallery, one guarding the entrance while the 

 others excavate and expel the borings. ^Ambrosia fungus is cultivated, 

 and then a few eggs are laid in the gallery, the young larvae feeding 

 upon the fungus. When these have attained a considerable size, 

 more eggs are deposited, and this process continues until there are 

 many larvae present, in all stages of development. These extend 

 the burrows, and during spring and summer, eggs, all stages of larvae, 

 pupae and adults may be found in the galleries. Females may leave 

 the colony from time to time to start new colonies in the same or a 

 different tree, but the original colony will continue to work in the old 

 tree as long as the moisture content of the wood is favourable to the 

 growth of their fungus. The adults apparently live for several years. 

 This species has a wide geographical distribution and a great range 

 of hosts. Pinus, Pseudotsuga, Picea, Abies, and Larix are among the 

 conifers attacked. It is found from the Atlantic to the Pacific from 

 Canada to Mexico and throughout Europe to Japan. The effect of 

 its attack is to weaken the vitality and hasten the death of the tree. 

 It also ruins lumber and affords entrance to detrimental bacteria and 

 fungi. The beetles Colydimn lineola, Say, and Clerus sphegeus, F., are 

 predaceous on it. Control measures must be chiefly preventive. 

 There is little danger of infestation in trees that are kept in good 

 growing condition, and where dying and dead trees are removed and 

 all broken and dead parts disposed of. For ornamental or shade 

 trees that have been recently attacked an application of coal tar 

 creosote will often destroy the brood and prevent further attack. 



Trypodendron lineatus, 01., penetrates the sapwood and heartwood, 

 the galleries branching considerably and the brood chambers extending 

 above and below the main galleries. Ambrosia fmigus furnishes the 

 food of this species and produces the characteristic stain on the wood 

 for some distance from the mines. Glischrochilus {Ips) fascicdus, 01., 

 is reported as predatory on the beetles, and probably Thaneroclenis 

 sanguineus is another enemy. This species is a rather serious pest in 

 recently felled timber, particularly of Douglas fir. To prevent loss, 

 felled logs* should be removed from the woods as soon as possible or 

 rolled into water. Most of the North American conifers are attacked. 

 T. ponderosae, Swaine, has been observed in Pinus ponderosa and 

 Pseudotsuga taxifolia, doing considerable damage to the sapwood of 

 recently felled Douglas fir. Gnailiotriclius retusus, Lee, mines the 

 sapwood and heartwood of injured, dying and recently dead trees, 

 logs, stumps and large limbs of Douglas fir. It occasionally attacks 



