26 



N. H. AGRI. EXPERIMENT STATION [l^ullctin 247 



This method of control can be used to advantage in smaller plantations 

 if practiced regularity during the years when the trees are at the age most 

 susceptible to attack. Of course if all white pine trees in the vicinity 

 are thus pruned the measure is more effective. Whether this method is 

 practical in large plantations is a matter for individual decision, accord- 

 ing to circumstances. Pruning the infested leaders is not ideal, for like 

 other methods it does not give absolute control. The trees attacked 

 are just as crooked as the ones whose leaders are not removed, but of 

 course fewer leaders are weeviled. 



The infested leaders should be removed the latter part of June before 

 the larvae proceed below the first whorl of lateral branches. Another 

 cutting the last of July will get those previously missed. Care is neces- 

 sary to prevent the removal of leaders which are injured from other 

 causes and which would have a chance to recover. 



When removed the leaders should not be left on the ground for the 

 larvae are able to complete development and emerge, thus offsetting all 

 the benefit that would be derived from pruning. 



Often the leaders are burned to destroy the weevils. This procedure 

 at the same time destroys beneficial insect parasites and predators, impor- 

 tant in reducing later attack. A method that will kill the weevils and at 

 the same time allow the parasites and predators to escape is to place the 

 collected leaders in a tight box or barrel covered with 12 or 14-mesh wire 

 screen. If 16-mesh wire is used many of the larger insect enemies are 

 unable to escape. The box or barrel must be tight to prevent the escape 

 of the weevils. It should be placed in such a position that water will 

 not collect and drown the beneficial insects. Leaders should remain a 

 year in the screened container, to allow time for parasites emerging late 

 in the season to escape and to make sure all of the weevils are dead. The 

 same container can be utilized from year to year. 



Experiments in New Hampshire in cutting off infested leaders show a 

 reduction in the percentage of weeviling after two years, (Table VI). 



In 1928 the trees in the Madbuiy plot were 11 — 13 years old; in the 

 Dover plot, 14 — 15 years old. From the figures in Table VI it appears 

 probable that a marked reduction in the Dover plot will be found in 1929. 

 It maj' be that the weevils that Vive over a second year are responsible 

 for the high infestation at Madbury in 1927. 



Table VI. — Removal of Infested Leaders 



