64 THE EEPORT OF THE No. 36 



Life Histoey and Habits. 



The beetles emerge from the ground during the latter part of May and early 

 June. In 1914, they were first detected on May 26, and during the next few- 

 days they were mating freely on the foliage. By May 30, eggs were being de- 

 posited. For the reception of the eggs the insect seeks cracks or crevices in the 

 ibark, such as spaces tiiat occur when the bark is Loose at stubbed ends of twigs 

 or branches. Loosened bud scales on twigs or wood, which have been removed by 

 pruning and allowed to remain on the ground, are also sought by the creatures 

 for the deposition of eggs. They appear to select any dry cavity in which the 

 eggs may be inserted, and which occupy positions tliat are exposed to the sun- 

 light. Eggs have been observed in situations on trees that were ten feet from 

 the ground, and doubtless they will be found in higher positions. The egg 

 measures about .2 mm. in width and .5 mm. in length. It is white, cylindrical 

 and gently rounded at the ends. Its shape seems to be influenced by the accom- 

 modation of the egg to surrounding surfaces. Eggs occur singly or in masses, 

 but usually in groups containing from twenty to eighty-five of them. Oviposition 

 is most active iduring early June. The period of incubation averaged betweeri 

 twelve and thirteen days with little variation under ordinary conditions. Upon 

 hatching the young larva wriggles out of its position of concealment in the bark 

 and falls to the ground. It then seeks a crack in the earth, when it quickly 

 disappears. The larvae apparently feed on tender roots, and our observations 

 indicate that they can live exclusively on the roots of willow, poplar and birch. 

 Doubtless they find subsistence on the root systems of other trees. It has not 

 been determined that they can live on the subterranean parts of grasses or weeds 

 which may be growing about the foregoing plants. The larvae transform to pups 

 during the latter part of April and early May. The pupal cells are considerably 

 larger than the larvae and are at an average depth of about two inches, although 

 some of them may be three inches in the soil. 



Methods of Control. 



The beetles are quite susceptible to arsenical poisons, and should it become 

 necessary to combat them little or no modification will probably be required in 

 existing spraying practices. Cultivation, if done with care and at the proper 

 time, would doubtless prove very destructive to both larvffi and pupas in the soil. 



The President: The State of New York certainly is a general stamping 

 ground for new pests. We have the Hyponomeuta, and now we have this other 

 Polydrusus which evidently by its abundance seems to be firmly established in 

 that State. I do not remember whether you mentioned in the paper any sugges- 

 tion as to how it came in. 



Dr. Glasgow: We cannot say with certainty, but probably in earth about 

 the roots of nursery stock. This is the only way apparently that it could get in. 



Mr. Burgess : I would like to ask Dr. Glasgow what success he has had in 

 its control. 



Dr. Glasgow: It is very readily controlled by arsenical poisons. 



Mr. Burgess: Do you use arsenate of lead? 



Dr. Glasgow: Yes. 



Mr. Burgess: At what strength do you use it? 



Dr. Glasgow: Commonly at the rate of three or four pounds of the poison 

 to fifty gallons of water. 



Father Leopold: At what time of the year do you use arsenate of lead? 



