Mr. P. J. Selby on the Fauna of Twizell. 363 



list boasts of a considerable number of generic forms as well 

 as species, and if our researches extended to the coast several 

 others might be added, such as Cleonus sulcirostris, Philope- 

 don geminatus, and plumbeus } Otiorhynchus tenebricosus,hc. &c. 

 Few species of the numerous genus Apion have been deter- 

 mined, but we have many more which require further investi- 

 gation and are therefore not included in the list. Cmjptorhyn- 

 chus Lapathi has only once occurred, the larvae were found in 

 the stem of a black poplar, and were first detected by the saw- 

 dust produced by the grub, and which was observed protru- 

 ding from the holes in the bark of the tree. Among the Bos- 

 tricidcB it will be observed that we have several species of the 

 genus Hylargus, and among them Hyl. piniperda and//, ater, 

 insects which have been considered as very destructive and fre- 

 quently the cause of the death of the Pinus sylvesiris. Of the 

 truth of this accusation we from the first entertained doubts, 

 which further observations for several years past have fully 

 confirmed, and we now feel convinced that the Hylurgus is not 

 the cause of the decay or death of the plant, but that it is in- 

 duced to deposit its eggs beneath the bark of the tree in con- 

 sequence of a prior disease from some other cause, and which 

 has brought it into that condition, in which it becomes the ap- 

 propriate nidus or breeding receptacle of these insects. I have 

 never found a healthy tree infected or attacked by them in the 

 larva state, every instance having occurred in such as had 

 previously shown decisive indications of ill health and decay, 

 a fact plainly exhibited in the colour of their leaves and stinted 

 growth. That they do some injury in the perfect state by 

 boring into and eating away the internal part of the slender 

 shoots in summer is not denied, but we never met with a 

 plant so severely injured in this way as to be the cause of its 

 death or indeed of any permanent injury. The catalogue of 

 the Lepidoplera amounts at present to 370 species and up- 

 wards, or full one-fifth of the whole order recorded as British, 

 and we think it not improbable from the number of species, 

 particularly the smaller yet to be added, that the proportion 

 may be increased to a fourth, an amount which would scarcely 

 be expected in so limited a tract of country ; had our confines 

 however been extended a few miles further, so as to embrace 



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