Aug. 1, 1SG7.] 



HARDWICKE'S SCIEN CE-GO SSIP. 



1G9 



LEAF-MINING LAEV.E. 



By H. T. STAINTON, F.R.S, &o. 



i HE most un- 

 observant can 

 scarcely have 

 failed to notice, 

 some time or 

 other, leaves of 

 plants with 

 pale blotches or 

 s on them. These 

 re formed by the 

 : of small insects, 

 which, feeding between the 

 skins of the leaf, devour more 

 or less of the green fleshy- 

 portion of the leaf, and so 

 discolour it. 



There are four orders of 

 insects which furnish us with 

 leaf-mining larvae, &c. ; but 

 two of these are not nume- 

 rously represented, and are comparatively seldom 

 observed. I allude to the mining larvae of saw-flies 

 among the Hymenoptera, and the mining larvae of 

 some of the weevils among the Coleoptera. The two 

 orders which furnish the great bulk of our leaf- 

 mining larvae are the Lepidoptera and Diptera. The 

 Biptera, or two-winged flies, a group of insects, 

 which, I am sorry to say, is very little studied in 

 this country, afford an amazing number of leaf- 

 mining larvae, and we see these mines constantly 

 on the leaves of the primrose, honey-suckle, butter- 

 cup, &c, &c. Those who search for the mining 

 larvae of Lepidoptera know only too well how very 

 plentiful the mining larvae of Diptera are; but 

 as the mining larvae of the Lepidoptera have been 

 the most studied, I propose now to confine my 

 remarks exclusively to them. Amongst the small 

 moths of the group Tineiaa, a group which com- 

 prises the smallest known Lepidopterous insects, 

 we have more than twenty genera of which the 

 No. 32. 



larvae are leaf-miners, or at any rate some of the 

 species in the genus adopt that mode of life ; for in 

 many genera we find a diversity of habit, and whilst 

 some of the species are leaf-miners in the larva 

 state, others are not so ; in other genera every 

 species without exception is a leaf-miner when in 

 the larva state. 



Sometimes the same leaf will be mined by two 

 or three species, each of which imparts to the leaf 

 a mark, recognizable by the initiated, indicating 

 what species has fed on the leaf long after the 

 larva has itself departed. A mined leaf is hence 

 inscribed with hieroglyphic characters, and the key 

 wherewith to- decipher these is obtainable by 

 patient and continued observation. 



To take, now, some particular instances: bramble- 

 leaves may frequently be found with two different 

 kinds of mines ; in one the leaf remains perfectly 

 flat, and a long slender serpentine gallery winds its 

 way across the leaf, and generally attains a length 

 of from two to three inches ; this mine, which is 

 scarcely visible whilst the larva is still at work, the 

 discolouration being then so slight, becomes very 

 conspicuous after it has been long deserted, the 

 dry loosened upper skin eventually becoming almost 

 white, and contrasting strongly with the dark 

 green colour of the leaf. The creature that makes 

 this mine is a small, pale amber, semi-transparent 

 larva, with no real legs, and when full-fed it crawls 

 out of its mine and proceeds to some convenient 

 comer in which it spins a small, flat, brownish- 

 green, silken cocoon, from which at the end of two 

 or three weeks there emerges a brilliant little moth 

 about a quarter of an inch in the expanse of the 

 wings, of which the fore wings are of a rich golden 

 brown, tinged with purple beyond the middle, and 

 with a nearly straight pale golden band beyond the 

 middle : this we call Nepticula aurella (fig. 174). 



Another kind of mine which we find in bramble- 

 leaves is very different ; the leaf does not 



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