BARK-BEETLES; ENGRAVER-BEETLES. 



225 



habits, and feed upon the same fungus. They are commonly as- 

 sociated in the same tree-trunk, and- not seldom occupy galleries 

 having a common entrance hole. Both species are known to at- 

 tack wine casks, but they probably breed only in dying trees."' 



The trees attacked include oak, hickory, beech, maple, aspen, 

 apple and orange, and the list might be extended to include other 

 hardwood timber. 



According to Fitch the insects sometimes attack young and 

 thrifty trees, which, when badly affected, are apt to suddenly 

 wither soon after putting forth their leaves, as if scorched by 

 fire ; the bark becomes loosened from the wood, and soon after- 

 wards these small beetles appear crawling through minute per- 

 forations, like large pin-holes, in the bark. 



Fig. 238. — Monarthrum fasciatum. 

 Say. .\fter Division of Entomology, 

 U. S. Department of Agriculture. 



Fig. 239. — Monarthrvm mali. Fitch. 

 .\ftcr Division of Entomology, U.S, 

 Department of Agriculture. 



From the above description by Mr. Hubbard it is seen that such 

 beetles are genuine gardeners, since they do not consume wood, 

 but minute and juicy fungi propagated on the walls of their gal- 

 leries. All the growing parts of the fungus are extremely succu- 

 lent and tender, but remain in that condition only \vhen contin- 

 ually cropped ; if allowed to go to seed it is no longer useful as 

 food. INIr. Hubbard also states that when their galleries are dis- 

 turbed and opened to day-light, the adult beetles generally fall 

 to eating their ambrosia as rapidly as possible. Like othe: social 



