THE CANADIAN ENTOMOLOGIST. 27 



all, it is usually by the primary or entrance galleries, which could cause only 

 the slightest detriment to the vitality of the tree. The most vital part of 

 a tree (the healthy living cambium) is seldom if ever touched by these 

 insects, since they make their entrance through the dead bark or wood. If 

 they did penetrate the healthy cambium, it would be no more than a pin- 

 hole, which, even in great numbers, could scarcely do harm, since in 

 healthy, growing trees such wounds would rapidly heal. 



This and other insects with like habits may, however, hasten or even 

 insure the death of unhealthy trees, since their entrance galleries may 

 contribute to the attack of harmful micro-organisms (bacteria and fungi) 

 which are ever ready to attack exposed plant tissue, and especially if the 

 vitality of the growing parts becomes in the slightest degree impaired. 

 This, it would seem, is the only way in which X. xylographus could affect 

 the vitality of the trees infested by it, but to what extent it may do so is 

 a problem for future investigation. It may, however, as suggested by 

 Hubbard, be the cause of serious defects in lumber manufactured from 

 trees or logs containing its pin-hole galleries and broad, leaf-like brood- 

 chambers. 



Preventives and Remedies. 



From what is known of the habits of the insect, it would appear that 

 the best methods of preventing its attack is to keep all fruit trees in 

 nurseries and orchards in a vigorous, healthy condition, and during the 

 winter, or previous to the first of April each year, destroy by fire all the 

 unhealthy or dying or dead branches on trees, thus destroying the 

 colonies before they emerge in the' spring. Wounds or dead places on 

 valuable trees may possibly be protected from the attack by the removal 

 of the dead bark and painting the dead surface, especially the edges, 

 with a strong solution of soap and water, undiluted kerosene emulsion, 

 melted grafting wax, or like substances. 



Diffei-ent Stages Briefly Described. 

 (See Plate 2.) 



Egg (fig. i) : Length, .52-.55 mm.; width, .24-26 mm.; yellowish 

 to pearly white ; shining ; ovate. 



Larva, first stage (fig. 2.): Length, ,60-66 mm. ; width, .20-22 mm.: 

 white ; head broader than thoracic segments, and yellowish, with pale 

 brown mandibles ; body slender, narrowing to last abdominal segment ; 

 head and each segment clothed with long, fine white hairs, longest on the 

 last three abdominal segments, Intermediate stage ; Length, 1.5-J.8 



