REPORT OF THE SOCIETY 113 



SEASONAL HISTORY. 



The moths usually emerge early in June; eggs are laid at once and hatch- 

 ing occurs in 10 daj's. The first winter is spent m the otter bark, and the 

 second within the inner sapwood. During the third season the larva works 

 in the heartwood, and pupation occurs that fall at the further end of the tunnel. 

 The following June the adults appear. That is to say, larvae hatched, for 

 example in the summer of 1920, will pupate in the fall of 1922 and emerge in 

 the summer of 1923. 



SUMMARY 



Prionoxystus macmurtrei Guerin-Menville, commonl}' known as the 

 Lesser Carpenter Worm, is a w^ood-boring, lepidopterous larva which tunnels 

 in red oak Querciis rubra, and "s confined in range chiefly to the eastern parts 

 of Canada and the United States. It will do great damage if allowed to remain 

 and breed for several years in the same stand, large trees being completely 

 ruined by its persistant attacks. Wood-destroying ants and rotting fungi 

 often accompany the borer's injuries. These harmful agencies working 

 within the trunk break down the woody tissus, reduce them to a rotten, honey- 

 combed mass and hasten the destruction of the host. The appearance of saw- 

 dust piles or small pellets of frass about the base of an oak forms a safe index 

 to the presence of the borer. Another reliable guide is the swollen canker-like 

 growths appearing on the trunks of the older trees which have been infested for 

 several seasons. These are induced by the tree itself in its endeavour to heal 

 the wounds made by the larvae. Broken down branches and stag-headed trees 

 also supply reliable clues. This form of injury is perhaps the most common 

 and most noticeable. 



The female moth resembles in many respects its widely known and more 

 destructive near relative, P. rohiniae, but may readily be distinguished from 

 it by the numerous black lines which cross thefore wings, ^ransi'erseZ?/; whereas 

 the very small male differs considerably^ from P. rohiniae, in size outline and 

 colour. 



Eggs are laid in June in the crevices of the bark, one female being capable 

 of depositing as many as two hundred and fifty or more. Hatching begins 

 in ten days. 



The larvae take three seasons to mature and attain a length of two and 

 a half inches, in the female. They burrow into the outer layers of the bark 

 where they spend their first season. The next 3'ear they continue their tunnell- 

 ing into the sapwood, passing the second winter in a somewhat bent or curved 

 position within the tunnel. During the third year, boring is entirelj^ within 

 the woody parts of the tree and this work is carried on until September when 

 preparations for pupation begin. The transformation takes place in a silk- 

 lined cell at the further end of the tunnel and the moths emerge the next 

 summer early in June. Occasionally, pupation is delayed till the following 

 Spring, and in such a case the emergence will also be later. 



Carbon bisulphide injected into the tunnels, which should be plugged 

 at once, is a successful means of control, and may be used to good advantage 

 in small areas. For extensive areas as in large parks, along highway's, and 

 forest lands, the following strong arsenical mixture will be found satisfactory: 

 5 lbs, lead arsenate. 

 40 galls, water 

 3^ gal. kerosene emulsion or miscible oil. 



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