Insects. 



8205 



Zygeena Minos in Ireland : the Extermination Question. — Zygaena Minos was in 

 great profusion in Ireland this summer, but did not appear until the first week in 

 July, being fully a fortnight later than in the hot summers of 1858 and 1859. I hear 

 it has also occurred on the west coast of Scotland, but not having seen any of the spe- 

 cimens I cannot speak as to their identity with the Irish insect. It is gregarious in 

 its habits to a singular degree : you may examine twenty of the stony fields so cha- 

 racteristic of the west of Ireland, all apparently alike in vegetation and aspect, and 

 not see a specimen except in one, but that one field will be positively crimson with this 

 beautiful moth. Much has been said about the extermination of insects, from their 

 wholesale capture by collectors, — more, I believe, than the facts warrant, — and though 

 I sincerely join in reprobating any needless takiug of life, I am inclined to doubt 

 whether it is in our power seriously to diminish the number of many insects by the 

 mere capture of specimens. As some evidence of this, in the case of Zygasna Minos, 

 I may state that I have taken from one rocky field, of perhaps fifty acres in extent, 

 upwards of 2000 specimens during the last five years, and thai the insect was this 

 summer more numerous than ever on the same ground. A female Z. Minos will lay 

 about 200 eggs, so that after all ray captures only amount to the produce of ten 

 moths for one season, and has probably had no appreciable effect on the numbers of 

 the insect. The destruction of woods, the alteration of the character of the soil and 

 its vegetation by drainage, and the encroachments of human habitations, are far more , 

 fertile sources of destruction to insect life than the ravages of the collector; but I do 

 not think that man, either directly or indirectly, is by any means one of the most 

 powerful agents in the extermination of species, though no doubt his sword weighs 

 when thrown into the scale. There seem to be not unfrequently causes at work which 

 deteimine the scarcity of one species and the abundance of auother closely allied in 

 habit, which are quite inappreciable by us; for instance, the common Burnet moth 

 {Zygcena Filipendul a) occurs on the same ground as Z. Minos, but in vastly smaller 

 numbers, probably not one Z, Filipendulas for fifty Z. Minos. Who can say why an 

 insect of such hardy habits and universal occurrence has not been able to get a strong- 

 hold in that locality, or what special enemy has put so effectual a check on its increase? 

 I can honestly say / have not hurt a hair of its head. The difference of habit in 

 Z. Minos and Z. Filipendulae would seem to favour the latter insect, Z. Filipendulae 

 forming its cocoon on the stem of a plant safely elevated above the effect of the almost 

 perpetual rain of the west of Ireland, whilst the cocoon of Z. Minos, placed at the 

 roots on the surface of the ground, must frequently be under water, and would seem 

 to be more exposed to the attacks of prowling beetles. Can it be that some insects are 

 like some opinions, — more apt to thrive under a little wholesome persecution than when 

 quietly let alone? — Edwin Birchall ; Birkenhead, September 16, 1862. 



[I very much agree with my correspondent's remarks on the extermination of 

 species by the hand of man : as instances I may cite Nematus ventricosus (the goose- 

 berry grub) and Pieris Brassicae (the large white butterfly), to destroy which man's 

 ingenuity and industry have been taxed in vain: it is a different thing when man 

 destroys the habitat, drains a bog, empties a pond or converts the heath into a corn- 

 field ; then the pabulum of life is gone, and life goes also. — Edward Newman.'] 

 . Description of the Larva of Melanippe procellata. — A number of eg^s of this species 

 were kindly sent to me by a friend at Brighton, about the end of July last. They 

 bafeehed almost immediately, and the following is a description of the full-grown 

 lam :— Head Hut, huffish brown and slightly hairy ; on the head are two reddish lines, 



