Insects Injurious to the Elm. 33 



channels figured at b in No. 2, has been styled topographus, 

 or "map maker/' from a supposed resemblance in the chan- 

 nels to the lines indicating rivers, etc., on engraved maps. 

 It is a rather larger insect than chalcographus, as shown 

 by the larva tracks, which may easily be compared, as the 

 traces of both are frequently found in the same tree. The 

 channel of another larva of this class has somewhat the ap- 

 pearance of writing, to which it is indebted for its specific 

 title autographus, while others have received equally charac- 

 teristic names. 



Mr. Westwood states that he has often fouud Hylisinus 

 Fraxini in the elm, though its name would indicate that its 

 ravages were confined to the ash. It is a small beetle, very 

 similar in form to the S. destructor, but it is of lighter colour — 

 the wing-cases being prettily variegated or clouded with a deeper 

 tone. The larva of Hylisinus Fraxini closely resembles that 

 of the genus Scolytus, and is found in a state of activity in the 

 elm during the month of August. The larvae of another little 

 beetle, enemy of the elm, of the genus Hylargus, very closely 

 resemble those of Scolytus. 



We have hitherto described the enemies of the elm among 

 the more minute representations of the beetle tribe., But the 

 British giant of the race — the great stag-beetle, whose con- 

 spicuous size and form soon make him well known to the merest 

 tyro among young entomologists — is also, in its larva stage, a 

 formidable enemy of this devoted tree. The larva of this large 

 insect is of proportionate size; and whenever it does attack a 

 tree of this kind, which is fortunately of not frequent occur- 

 rence, as the insect is not very abundant, the dangerous nature 

 of its inroads may be easily conceived, as it not only bores into 

 the very heart of the wood, but also, with still more fatal effects, 

 penetrates the main roots in a similar manner. A tree-enemy 

 upon fully as large a scale, is the Cossus Ligniperda — the wood- 

 boring Cossus. This is a large moth, one of the handsomest 

 our British kinds ; the caterpillar of which is large, and protected 

 with strong scales, and also furnished with powerful mandibles, 

 which enable it to eat its way into the core of the hardest woods. 

 It prefers, however, the pear and the willow, but is frequently 

 found in the elm and other large forest trees. The damage 

 done by this powerful larva to the trees it attacks may be 

 readily imagined, as it lives from two to three years in the tree 

 before its transformation takes place ; and at its full growth 

 leaves a clear bore through the solid wood of from half an 

 inch to three-quarters of an inch in diameter. 



There are many interesting circumstances known regarding 

 the habits of the Cossus Ligniperda ; but the present paper has 

 reached its extreme limits, which also prevents the description 



VOL II. — NO. I. D 



