trees of this grrup. Thus the tree killing or primary 

 "beetles are in three groups: (1) the Ipidae (formerly 

 Scolytidae) of the genera Dendroctonus, Ips, Eccoptogaster, 

 etc., commonly called "bark beetles; comparatively small beetle, 

 with pitch tubes or sawdust evidence of their wcr>, egg gal- 

 leri^n and rov.nd exit and entrance; holes; (2) the L^prestidae 

 of the genus llelanophila, much larger beetles, often 1/2 to 1 

 inch in length with flat larvae, the front or ' T hea6 '' being 

 much broader than the rest of the bcdy and having a flat 

 appearance, hence the name "Plathead Borer". The exit holes 

 are elliptical with no entrance holes which can be distinguish- 

 ed, the eggs beinp; laid in the crevices of the bark anri the gal- 

 leries distinctly widening as the larvae grow; and (3) the Cer i. 

 bycida^ of the genus Tetropium or "Roundhead Borers", with 

 larvae with a round front v/ith the rest of the segments n nly 

 slightly narrower and not flat. With the exception of the 

 ab^ve genus, the roundhead borers are generally secondary, 

 ha^e round or nearly round exit holes and no visible entrance 

 holes, the eggs also being laid in the crevices of the bark. 

 These beetles are generally of large size and have long an- 

 tennae, sometimes called feelers or horns. In the following 

 general description of the various tree -killing beetles at- 

 tacking conifers in California, the distinguishing features 

 of adult habits and design of egg galleries and larval gal- 



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