32 FOREST PROTECTION 



(11) Watch for spider webs showing saw dust; for drops of rosin (pitch 

 tubes) appearing on the bark; for a local increase of woodpeckers indicating 

 an increase of food material; for a slight change in the tint of the pine-crowns. 



(12) Apply sprays or washes, twice or thrice per season, to particu- 

 larly valuable trees (Forest Bui. No. 22, p. 56), e. g., lime and Paris green, 

 mixed to a mass of light green color; or soft soap, adding enough washing 

 soda and water to reduce the mixture to the consistency of a thick paint; 

 or a thick wash of soap, Paris green and plaster of Paris; or a mixture of one 

 pint of carbolic acid, one gallon of soft soap and eight gallons of soft water. 

 Arsenate of lead may be used instead of Paris green, and has a greater in- 

 sect icidal value. 



B. AGAINST BUPRESTID^ AND CERAMBYCID^: (FLAT-HEADED 

 AND ROUND-HEADED BORERS). 



(1) Prepare trap trees, or use trees accidentally injured or weakened 

 as such. 



(2) Remove, peel, burn or immerse in water, trees in weakened con- 

 dition. Begin logging in districts containing such trees (e. g., blowdowns, 

 burns). 



(3) Prevent ground fires which weaken the trees, burst their bark and 

 render them liable to successful attacks by Buprestids and Cerambycids. 

 Try to retain the fertility of the soil. 



(4) Protect insectivorous animals (compare Bureau of Entomology 

 Bulletin No. 28, p. 23.) 



(5) Prevent trees left in the course of logging from being recklessly 

 injured by axe, by felled trees striking them, etc. 



(6) Where you remove a portion only of the trees standing in the woods, 

 log in winter (not in spring and summer). 



C. AGAINST CURCULIONID.E ("BARK WEEVILS"). 



(1) Remove the trees which appear injured by axe, lightning, storm, 

 sleet or the fall of a neighbor. 



(2) Prepare trap trees, and destroy the brood of Curculionids develop- 

 ing therein in due season. 



D. AGAINST PTINID.E. 



Mind that the bark is safe from powderpost beetles for two years, and 

 do not store any tan bark for more than two years. 



