416 RHTNCHOPHOEA. [Hijlesinus. 



the case of H. fraxini, as observed by Dr. Chapman, the female is 

 often bulkier when the burrow is half completed than on entering it, 

 and the eggs laid by a single beetle must often exceed in aggregate mass 

 the original bulk of the female. The eggs are laid along both sides of 

 the burrows, usually at very regular intervals, in little hollows dug out 

 to receive them ; they are covered with a gummy material, which soon 

 gets a coating of fine frass ; the gallery is finished and the eggs laid in it 

 in from ten to twenty days ; when the task of oviposition is finished both 

 beetles usually die in the burrow ; the female always does so ; the dead 

 beetles may still be found lying in the burrows after several years ; the 

 larvae are straight, white, footless fleshy grubs, with a rather large head 

 and powerful mandibles, and appear to hatch out towards the end of 

 May. In the autumn they assume the pupa state, and shortly after- 

 wards emerge as perfect insects. In cases where the beetles attack 

 young trees it is a good plan to rub a good coat of soft soap into accessi- 

 ble parts of the tree by means of a common scrubbing-brush ; some 

 authorities are of opinion that it is the want of dying timber that forces 

 them to attack the live trees, and advise that the old trunks should be 

 left as traps, whereas others consider that these harbour the beetles, and 

 advise their removal ; if the old trunks or pieces of trunks are burnt at 

 intervals, it is probable that the plan of leaving them on the ground will 

 be found to be of service. 



Dr. Chapman has made an important observation with regard to H. 

 crenatus, viz. that it takes two years to undergo its transformations, the 

 larvae assuming the pupal state at the end of the second summer ; as 

 felled timber would be unable to support this long larval existence, the 

 beetle is never met with except in living trees, and, while an aifected 

 tree continues alive, they appear never to desert it for another ; " they 

 economise it," Dr. Chapman says, " as much as possible, the destroyed 

 bark being more completely riddled and devoured by them than by any 

 other beetle of the family I am acquainted with ; the burrows of the 

 larvae are much more irregular also, so that it is impossible to find one 

 of those perfect maps of their voyages (as in H. fraxini), which have 

 earned for the Xylophaga as a family the name of ' typographers' " 



H. vittatus attacks fallen elm, as H. fraxini does the ash ; its burrows 

 are shorter, and the two branches are very uniformly of equal length, 

 rarely exceeding f of an inch long ; the number of eggs laid is seldom 

 as many as twenty, and, being usually placed more widely apart 

 than those of H. fraxini, the burrows of the larvae are nearly parallel ; 

 the species never appears to attack live trees and is therefore unimpor- 

 tant from an economical point of view. 



It should be remembered that all these beetles that bore into the solid 

 wood play a most important part in clearing the ground of dead trees : 

 this is especially the case in the tropical forests, which would utterly be 

 choked up and destroyed in the course of ages but for the insects that 

 drill holes into them which admit the moisture that causes them to 



