396 NEW YORK STATE MUSEUM 



the life of a colony, and as a rule only two or three generations occur in 

 a large tree trunk, while in smaller ones there may be only one brood. 



A typical life hist(>r\' of these insects is well ilhistrated by Mr Hubbard's 

 account of X )• 1 e b o r u s pubescens Zimm. A solitary female starts 

 the galleries similar to those illustrated in figure 104. Fhe branches serve 

 as brood galleries and in each, five to six oval, pearly eggs are deposited. 

 The )'oung hatch within a week and begin teeding on tlie ambrosia at once. 

 The pupae lie free in the galleries, and in somewhat over a month from 

 the eggs perfect beetles appear. The colon)-, in time, contains beside the 

 mother insect 15 or 20 aelult oftspring, most ot which are females, only one 

 or two males commonly being found. A second brood is started by this 

 later generation, Init the seasoning of the wood and threatening failure of 

 food usuallx' warn the )Oimg females to depart antl seek fresher trees. 

 This leaves the abandoned males in a sad condition, since they are unable 

 to consume the ri])ened amlirosia, and they als(j wander fni-tli, though wing- 

 less and weak, or are suffocated !))■ the superabundant fungus. Sometimes 

 they assemble in certain galleries and form bachelor colonies, where by 

 united efforts they are able to check the fungus and jM'olong existence for a 

 time. The watchful care of the mother for the young is well described in 

 the notice of M ( > n a r t h r u m m a 1 i T itch, page 29 1 . 



These little insects are of economic importance, [jrincipally on accoiuit 

 of their injury to timber. A few sjjecies are known to affect ]i\'ing trees, 

 though as a general rule their attacks are confined to dying or dead timber. 

 The defects in the wood caused by the galleries of these beetles, and the 

 stains left by the fungus, probably entail more loss than the injury caused 

 by attacks on living trees. The presence of their galleries seriously depre- 

 ciates the value of timber used as cask heads, staves, shingles and the like. 

 These defects may l)e repaired to some extent l)y plugging, Ijut those made 

 by some species cannot be tluis treated. It is possible in some instances to 

 take advantage of the haljits of the insects, and by proper sawing the 

 damage may be reduced to a minimum. The softwood in the Adirondack 

 region is s(;riously affected by these little borers, and the quality of much 

 of it greatl\- impaired. 



