104 



MISC. PUBLICATIOX 273. U. S. DEPT. OF AGRICULTURE 



groups. (1) in June. (2) late in July and early in August, and (3) 

 in September. XeAY attacks are made immediately after emergence, 

 and the resultant broods develop to new adults, mature larvae, or 

 small larvae before tlie cold at inter weather again stops develop- 



.f^, 



> 



FiGUEi; 



~,^-:,_.--. :.]i'[ 'j-i'i':-! -■■;:; '''- 'li- ii-uiraiii piiie beetle [Dtiidroctonuv monti- 

 cularj. Adults, larvae, and pupae, at lower riglit. Natural size. 



ment. formally there is only one generation a year, but owing to 

 the uneven development there is considerable overlapping of the 

 various broods, so insects in all stages may be found at any one time 

 during the siunmer. Late fall, winter, or early spring is therefore 



the best time to carry on control work. 



