CATALOGUE OF INSECTS. 361 



Family SCOLYTIDiE. 



These are the "bark-beetles." They are usually cylindrical, or nearly so, 

 often with the end of the elytra truncate and sometimes armed with teeth in 

 the male, the head bent down and retracted, often overshadowed by the pro- 

 thorax, which may be rugose or otherwise roughened anteriorly, the legs short 

 and capable of being closely folded to the body. They are borers in wood or 

 bark, sometimes making galleries in the heart wood, sometimes remaining in 

 the cambium layer and mining partly in the bark and partly in the wood. In 

 the latter case the parent beetle usually makes a central gallery along the sides 

 of which eggs are laid: the larvae hatching from these eggs make galleries of 

 their own, increasing in size as they diverge from the center. When full grown 

 they pupate at the end of their galleries and emerge as adults through little 

 round holes. Of this type is the common fruit-bark beetle. 



Others that bore in the heart wood differ in habit. Here in many cases the 

 parent beetles make the galleries which serve for the propagation of a peculiar 

 fungus growth termed Ambrosia, and upon this the larvae as well as the adults 

 feed. The habits of some of these beetles are very interesting. 



It is perhaps a rule, though there are many exceptions to it, that these insects 

 attack only trees that are not entirely healthy or have been injured locally or 

 generally. The type making galleries in the sap wood conform to this rule 

 quite usually. 



To this class belongs the worst pest of this family that we have in New 

 Jersey, the fruit bark beetle, and here we should stimulate and keep our trees in 

 healthy, vigorous growth to avoid injury. A tree that once becomes generally 

 infested by this beetle had better be taken out at once and burnt. 



Against species that attack healthy trees we have no remedy ; but fortunately 

 these are rare in New Jersey and none of them attack our orchard trees. 



Mr. A. D. Hopkins of the West Virginia Experiment Station has kindly 

 assisted in this family and is authority for most of the notes on the food habits. 



PLATYPUS Hbst. 

 P. flavicornis Fabr. Anglesea, V, 21 (W, Sm). 



CORTHYLTJS Br. 



C. p-diictatissimus Zitnm. Eagle Rock (Bf), Staten Island (Lg), bores into 

 sassafras, entering green wood (Hp). 



MONARTHRUM Kirsh. 



M. fasciatum Say. Found throughout the State, V-VIII : attacks living 

 trunks of hickory, beech, oak, &c. (Ch) ; enters green sap and heart- 

 wood of dying and dead trees, logs and stumps of pine, oak, hemlock, 

 &c. (Hp). 



M. mali Fitch. Orange, VI (Ch), Eagle Rock (Bf), DaCosta (W), rare: 

 habits like the preceding and has an even larger range of food plants, 

 including apple. 



