220 GEOLOGICAL SURVEY OF NEW JERSEY. 



enough for practical purposes. A very striking character in 

 some species is that, while they really bore into the wood, yet 

 the larvae have to be fed by a peculiar fungous growth known 

 as Ambrosia. All the real boring is done by the adults, and the 

 galleries once seeded down to Ambrosia-zxe inhabited by succes- 

 sive broods of species, the dark staining in the wood resulting 

 as much from the fungus as from the work of the beetles. On 

 small trees a number of these beetles working at or near the 

 same place may so weaken the trunk that it will break in the 

 first high wind that comes along. 



Other species seem to prefer the very center of twigs, boring 

 out the minute core in oaks and using the galleries thus made 

 as a winter shelter. 



The round-headed borers are more or less cylindrical, white 

 or yellowish grubs, the segments usually very well marked, and 

 the "head," or anterior portion, considerably enlarged or 

 swollen. These forms frequently attack living wood, and bore, 

 usually, in the solid tissue, though some may burrow, for a time 

 at least, beneath the bark or in the bast. To this series belong 

 the "oak pruners," the "twig girdlers," the "bark slippers" 

 (concerning which more will be said hereafter), the " giant root- 

 borers," and a variety of other pests. The adults are Longi- 

 corns, or long-horned beetles, and all are feeders in woody or 

 stem tissue in the larval stage. As adults they are not injurious, 

 and are apt to be found on flowers, though some species are dis- 

 tinctly rare even when their larvae are not uncommon. Thus 

 oak sprouts are attacked at the base by a borer which kills a 

 large percentage of them each year, and this borer is not at all 

 rare ; but the beetle, Goes tessellatus, may be sought for years 

 before even a single example will be captured. 



As an example of the injury done by these longicorn borers, 

 that attacking the locust may be cited. There is scarcely a 

 locality in the State where these trees are not rendered utterly 

 worthless by the attacks of these insects, and, while the trees 

 may live under the attack for years, they are never good for any- 

 thing. And this leads me to call attention to another point : 

 the longicorn borers are mostly wood feeders, and when they 

 attack healthy trees, as many of them do, they bore at once into 

 the trunk or the bodv of the branch. If they work in the bast 



