Tnsecis. 611 



cieshave therefore been well ascertained, and the Germans especially, whom the policy 

 of their governments has commissioned to enquire into such things, have so com- 

 pleted the biography of many species as to leave nothing else for future observers to do, 

 but to add the lives of the remainder. Those kinds whose habits have been thus in- 

 vestigated, are Tomicus Laricis, typographus, orthographus, pinastri, abietiperda and 

 chalcographus, Hylurgus piniperda, Trypodendron dispar and Scolytus haemorrous 

 and destructor. The kinds whose economy is still obscure, are chiefly those belonging 

 to the genus Hylesinus, and it would require but a moderate degree of industry to 

 complete the whole history of this interesting group of insects. Hylesinus Fraxini is 

 an obscure beetle, about one sixth of an inch in length, and, as its name implies, af- 

 fects particularly the ash tree. It is rather prettily variegated with marks of light and 

 dark brown, the female being distinguished from the male by being a trifle bulkier, 

 and deeper in colour. The period of their greatest activity is the sunny days of early 

 spring, about the months of April and May, when the perfect insects are developed 

 from the pupa state ; they are then found flying about in numbers in the neighbour- 

 hood of ash trees, either the young tree, the branches, or the main stem of older growth, 

 and also ashen poles used in palings. After pairing, the little creatures commence the, 

 work which is the main object of their existence. The female selects a place in the 

 bark, perhaps preferring a smooth pole, where there is a little roughness, and begins to 

 bore, applying its short- snouted mouth to the surface, and twirling round, sometimes 

 even rapidly, and forming in a marvellously short space of time a cylindrical hole, suf- 

 ficiently large to receive half its body. At this stage of its proceeding, I have invari- 

 ably observed that the male comes to her assistance, places his head and fore feet on 

 the tip of her body, and employs all the energy his little frame is capable of, in thrust- 

 ing his mate into the interior. In this singular work the male evinces extraordinary- 

 anxiety, vibrating his antennae and moving rapidly round the disappearing body of his 

 fellow-labourer. When both the insects are within the inner bark of the tree, they 

 close the entrance, whether accidentally or designedly I do not know, with the dust of 

 the outer woody part of the bark. From this cause it is impossible, on a superficial 

 glance, to judge of the enormous amount of destruction which these little creatures are 

 capable of effecting in a short time. The pole whereon I observed their habits was 

 newly cut from the tree but a few days, before fresh galleries were drilled under the 

 bark in every part of it. In the boring of these galleries they work transversely across 

 the stump, the male and female diverging when they have effected an entrance. Some- 

 times I have seen the two in one gallery, but my impression was that the one had run 

 to the other through the alarm occasioned by cutting open the place. It is also a pe- 

 culiarity, that when two different galleries approach each other, one of them always 

 diverges, their mutual approach being doubtless made known by the gnawing in the 

 wood, thus the course of one family never interferes with that of another. The male 

 soon dies, but the female continues to deposit her eggs, which evolve in a few days a 

 whitish grub, as voracious as its progenitors. There are other species of this and other 

 genera in the family, whose habits are perhaps equally interesting with those of the 

 preceding species. We have Hylesinus crenatus in the rough bark of those ash trees 

 which Sinodendron cylindricum has disfigured, and H. sericeus in palings made of 

 poles of fir timber. There are also a species of Tomicus in larch poles, and a Hylas- 

 tes of equivocal designation in the bark of those oak stumps which have been cut down 

 in our woods. — H. W. Bates ; Leicester. 



