UNITED STATES IEPABTME1TT OP AC-RICULTUBE 

 Bureau of Entomology 

 Washington, D. C. July 15, I3c5* 



rest Entomology Brief 60 



THE SOUTHSM PISE BEETLE 



A Menace to the Fine Timber of the 

 Southern States 



LIBRA R Y 



★ JIM 50 1925 * 



The southern pine beetle is a small brownish or black beetle, 

 about the size of a grain of rice, that attacks the trunks of 

 healthy pine trees, causing their death by excavating long, wind- 

 ing burrows, or egg galleries. These extend through the inner 

 layers of the living bark and mark the surface of the wood. After 

 the tree is dead a new brood of beetles develops in the bark (from 

 the eggs deposited by the parents which killed the tree) and soon 

 emerges to fly in search of other living tress, in which this pro- 

 cess of attack and development is repeated. 



Causes of Outbreak 



Ordinarily the southern pine beetle is a rare insect in 

 our forests. Periodically, however, when climatic conditions 

 are favorable, it rapidly increases to enormous numbers, destroy- 

 ing great quantities of pine, and then disappears just as suddenly. 

 Investigations of the Bureau of Entomology .have indicated that 

 abnormally dry spells produce favorable conditions both in weak- 

 ening the tree and in producing a more suitable situation in the 

 inner bark for the rapid development of the broods of the beetle. 

 'The resinmption of normal or heavy precipitation ef fectiveljr checks 

 such development and practically eliminates the beetles from the 

 forests. 



Evidence of the Pe struct ive Wo r k of the Beetle 



The presence of this beetle in dangerous or destructive num- 

 bers is plainly indicated by patches of dying and dead pine which 

 show no evidence of injury by fire or other destructive agencies. 



Trees infested by the developing broods are indicated by 

 fading green, greenish -brown, and yellowish-red foliage and can 

 be positively determined by the removal of some bark from the 

 middle of the trunks of the dying trees. Here the characteristic 

 winding s-shaped galleries in the inner bark and on the surface 

 of the wood can be found, and by removing the outer bark the de- 

 veloping broods can be seen. 



