6 



each side, in small creiiules, she deposits her eggs as she advances, and closes the 

 aperture with some plastic material; tlie number of eggs is in proportion to the length 

 of tube (and this is very much influenced by the condition of the under surface of 

 the bai'k, for if the Scolyti abound the parent ceases boring, so as nut to perforate the 

 workings of another when she approaches it) ; only a small septum divides each ; there 

 are generally from 60 to 70. On bursting their shells the young larvas immediately 

 commence feeding on the last deposit of alburnum ; they at first form parallel trans- 

 verse lines or tubes, which are seen to gradually enlarge and diverge, and are filled 

 with exuviffi as the larvce progress onwards ; their increasing size now oblige those 

 larvaj first hatched to bore downwiirds, the centre ones outwards, and the last upwards ; 

 here they C(mtinue to feed during the summer, autumn and winter (if mild): when 

 full-grown tliey form a case, in which they chaufje to the pupa state; and then, at tlie 

 end of May or beginning of June, they eat their way out through the substance of the 

 bark, and leave those shot-like holes showing their plan of exit: they now fly about 

 for a short time, and then the females commence the process for perpetuating their 

 species, by laying their eggs. I believe after they have once commenced boring and 

 depositing their ova they never take wing again : as soon as the female has deposited 

 all her eggs, with her head pointing inwards, she dies at the entrance of her tube, 

 thus, as it were, even in death performing a maternal duty, by closing the aperture to 

 her young ones with her dead body. It is very rare to find a parent tube without the 

 insect, allhouuh no doubt they occasionally become a prey to various smaller insects. 

 It is the frass the female ejects from the tube that leads to the detection of the pre- 

 sence of the brood, for were it not for this fortunate circumstance we should never be 

 apprised of the destruction going on within the tree until the escape of the mature 

 insect, in spring, shows the exit-holes. ^ 



" I will not trespass more now into detail, but simply state that each family will 

 destroy nearly four square inches of bark. Granting, therefore, even the possibility of 

 the Scolyti being attracted by the sickening state of a tree, here we find one parent 

 insect has the power of destroying a large portion of bark, and consequently must 

 rapidly hasten the final decay. No doubt where the insect abounds it will perforate 

 the bark of fresh-hewed timber; but I have never found one specimen in an elm 

 whose juices were dried up. Therefore, irrespective of the cause of disease, it must 

 be unanimously granted that an insect which can destroy four square inches of bark 

 by detaching it from the alburnum must prove highly destructive, and, whilst permit- 

 ted to remain, frustrate any attempt to restore health. If, in the absence of any 

 true and logical cause, we have found elm trees sickening and dying, and their bark 

 bearing the unequivocal signs of the Scolyti, and simply by a process of partial bark- 

 ino- and removing the Scolyti huvse, we arrest the decay of those not too far advanced, 

 and in a comparatively short period restore them to health and beauty, we have every 

 rational right to infer that the Scolyti, and the Scolyti alone, were the aggressors in 

 the first instance, and destroyers in the second ; and still more, that when we find the 

 whole of the diseased trees in the Royal Botanic Gardens perfectly recovered in 

 1849 and now (1858) bearing all the impress of vigour, so that in many the fearful 

 scars once made are now hidden from sight, and buried by the overlapping of suc- 

 ceeding yearly deposits, I think this Society will ask no further proofs at my hands of 

 the sound and practical results that have followed the simple and easy process of par- 

 tial barking; that the lapse of so many years establishes beyond a doubt its great 

 utility ; and that, in the absence of any other advanced system for arresting the spread 



