lt)C8. J 



121 



are often to be seen swarming about fresh ash logs ; they arrive on the wing, 

 preferring the warm sunshine of the early morning for their flight, and often 

 travel considerable distances. They bore very rapidly into the bark. The femalo 

 commences the gallery by boring obliquely towards the wood, usually in a 

 slightly upward direction, in large timber choosing the deepest part of a crevice 

 of the bark ; in younger wood a knot or other irregularity determines the preference, 

 80 that, unless the frass lies about the aperture, they are difficult to detect. 

 Usually before the female beetle has quite bm-ied itself in the bark, the male 

 arrive^, and is waiting to enter the burrow ; if not, the female bores down to the 

 wood, and there awaits his coming ; and I believe I have met with burrows 

 uncompleted because the male insect did not appear. In a few days the two beetles 

 are to be found rapidly extending the gallery in both directions from the aperture 

 of entry, close to the wood and usually slightly in it, and transversely to its fibres. 



I suspect each of the beetles excavates a branch, but I have found no means of 

 observing them at work, as opening the gallery always stops them ; and it is 

 possible that the female does the greater part of the excavation, since I have 

 always found her further from the aperture of entry when both were in the same 

 branch of the burrow ; the male is also oftener at its opening, and eggs are laid 

 along each as rapidly as it is formed. Not unfi-equently the branches of the 

 gallery are of very unequal length, so much so that sometimes there is practically 

 only one branch, possibly both beetles working togethier. Undoubtedly the gi^eater 

 part of the excavated material is eaten ; and I find that in captivity the beetles 

 will hve a long time with fresh ash bark, though without it they soon die. Most 

 insects on thefr escape from the pupal state contain their eggs ready to be laid and 

 requiring only fertilization, but in these, as in many more active Colec/ptera, the 

 eggs are developed after attaining the perfect state. In the case of H. fraxini 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 domestic habits and family relations of these 

 beetles deserve further attention. The following suggestive experiment was made : 

 a burrow was opened, in which some few eggs had been laid ; each beetle was then 

 blockaded by a bit of bark in a branch of the burrow, and for each sufficient space 

 was left for air and the discharge of frass. A week after, each beetle had eaten a 

 narrower buiTow just long enough to hold it, merely to sustain life, contrasting with 

 the wider burrow outside ; but no eggs had been laid. 



The eggs are laid along both sides of the burrows, usually at very regular 

 intervals, in little hollows dug out to receive them, leaving the gallery of full size 

 for the beetles within it. They are covered with a gummy material, which soon 

 gets a coating of finer frass. These eggs being laid in rotation, form a good series 

 for observing the development of the larvae within the egg, the first being often 

 hatched and the young gi-ub boring into the bark before the last is laid. The eggs 

 laid in one burrow vary from 15 to 40 or 50, or even GO to 100. The gallery 

 is fijiished and the eggs laid in fi'om ten to twenty days. During the ejection of the 

 frass, particles adhere by a gummy matter, and form an operculum to the mouth of 

 the burrow, leaving only a minute opening for frass, which on the completion of 

 the burrow is stopped up. Both beetles then usually die in the burrow ; the 

 female always does so. The dead beetles may still be found lying in the burrows 

 after several years. 



