October, 1929] WHITE PIXE WEEML 5 



tions are distinctly punctured. The legs are strong, .^ubequal. The tibiae 

 have an incurred spine at the apex. The tarsi are sliort and broad. The 

 tarsal claws are simple. The length of the adult varies from 4.0 mm. to 

 6.9 mm., the average being 5.2 mm. 



INJURY 



Exudations of small clear drops of i)itch from the punctures made in 

 the upper part of the leader are the first evidence of injury. The pitch 

 ma\- later run down the stem or remain in small spots which become 

 white upon hardening. Often injury- is not noticed until the lar\-8e cause 

 the 3'oung growth to become discolored and wilted. Later in the sea- 

 son the appearance of dead tips indicates further development of the 

 insects in the leader. 



The most important injury, readih- observed, is confined to the ter- 

 minal shoot or leader of the white pine, usually extending only as far 

 as the first whorl of lateral branches. 



After the terminal .portion has been killed bj' the feeding of the larvae 

 the lateral branches next below tend to grow more upright the follow- 

 ing 3'ear and to compete for the place of leader. The longest lateral 

 branch assumes this role. In some cases two laterals will maJie approx- 

 imately the same growth and both will replace the dead leader, resulting 

 in the formation of a forked tree. Rareh* three or even more laterals 

 exhibit this phenomenon. 



When a lateral branch replaces a leader the trunk of the tree has a 

 bowed appearance between the nodes where the replacement has taken 

 place. The number of times a tree has been attacked can readily be 

 calculated by the appearance of the internodes and by the remains of 

 the killed leader, which can often be found projecting from the side of 

 the trunk, even mam* j-ears later. 



The host tree ma}- be injured repeatedly from the time it is about 

 five years old until it reaches maturity. In general, the most extensive 

 injury- takes place when the trees are from eight to eighteen j-ears of age, or 

 from five to fifteen feet high. The weeviling gradualh- declines as the 

 trees approach maturity. It is surprising to note the number of trees 

 thirt}- or more feet high showing recent weevil injuries. The height of 

 the older trees makes the injury less noticeable and has led to the gen- 

 eral belief that trees over thirty years of age are rarel}^ attacked. 



Graham (1926) has shown in the relation of injury to crown class and 

 rate of growth that the weevil seems to choose the most thrifty and 

 rapidly growing trees in a stand, not necessaril}^ the tallest trees. 



Experiments were carried on to note the preference, if any, for dom- 

 inant and recessive leaders. A dominant leader of large tip diameter 

 is a good indication of the relatively vigorous condition of the tree by 

 which it was produced. A screened cage four feet long, two feet wide, 

 and eighteen inches high with three-eighths inch holes spaced five inches 

 apart in the wooden floor was used in the experiments. Twenty-two re- 

 cessi\-e leaders, one-quarter inch in tip diameter and thirteen inches 



