ELISHA MITCHELL SCIENTIFIC SOCIETY. 75 



served several which lived for two months always at the post of 

 duty. Even in death they remain blocking the entrance, and it is 

 a very common thing to find them attacked by a fungus and their 

 bodies wedging up the entrance firmly. 



Eichoff speaks briefly of this habit in Scolytus\ where he says, 

 "das Weibchen meist im Gange selbst stirbt, entweder am riusser- 

 sten ende seines Brutganges oder (bei den einweibig lebenden Ar- 

 ten) wie bei Scolytus (Eccoptogaster) nachdem es sich an die Ein- 

 gangsoffnung begeben und dlese zum Schutz gegen iiussere Witte- 

 rungseinfliisse und vor eindringenden Feinden, den After nach aus- 

 sen gekehrt luft verachlassen hat." 



From specimens in the laboratory I bred two parasites, which 

 were determined by Mr. L. O. Howard, of Washington, as follows: 

 Chiropachys colon. Linn. And Eupelmus sp. The Chiropachys, 

 Mr. Howard tells me, has been bred from the larvae in the Depart- 

 ment at Washington. When these parasites transform into the 

 adult they e.^^cape by cutting a cylindrical hole through the bark. 

 Some of these holes are as small as .25'"'" in diameter. From an 

 examination of infested branches of peach trees I find that the par- 

 asite is quite abundant, and it undoubtedly is quite efifective in 

 checking the multiplication of the Scolytus. 



^Die Europaischen Borkenkafer, i88i. 



Note. — I wish to acknowledge my indebtedness to Prof. C. V. Riley, of 

 Washington, for the use of some literature from the Department; and to Mr. 

 E. A. Schwartz for a work from his private kibrary. 



