16 HOUSE, GARDEN, AND FIELD 



parent epiderm. The mine becomes filled with air, and 

 at length shows up strongly against the dark ground of 

 the leaf. When the larva begins to mine it is very small, 

 but as it grows bigger, it excavates for itself a wider and 

 wider gallery. It is easy to turn it out with a needle, and 

 observe the yellow, translucent body, tapering behind. 

 The usual three pairs of thoracic legs are wanting, but 

 there are some imperfect abdominal legs. Legs are often 

 deficient in such insect-larvse as are enclosed in their food, 

 and have no motive for moving far. When the season 

 for pupation is at hand, the larva quits the leaf, which has 

 hitherto provided it with food and shelter, and spins for 

 itself in some safe retreat a flattened cocoon, within which 

 it changes to a pupa. After two or three weeks the moth 

 emerges. It is only about a quarter of an inch long, with 

 brownish- yellow fore wings, becoming purple towards the 

 tips, and a pale yellow band beyond the middle. I know 

 of no English name for it, but its technical name is 

 Nepticula aurella. The hind wings are furnished with 

 long fringes, a peculiarity not uncommon in insects of 

 different kinds. 



Another minute, fringe-winged moth (Tischeria mar- 

 ginea) is also common on the bramble. The larva is 

 most often found in winter, and may be recognised by 

 the shape of its mine. Beginning very narrow, it soon 

 expands into a large irregular blotch, which occupies 

 perhaps a third or a fourth of a leaflet. The insect 

 pupates within its gallery. 



When you have once begun to notice leaf-miners, you 

 will see them everywhere, on buttercups, cow-parsnep, 

 dock, celery, and many other plants of the field and 

 garden. You will find that most of the leaf -mining larvae 

 turn either to moths or to two-winged flies. Each species 

 keeps as a rule to its own kind of plant. There are also 

 leaf -mining saw-flies and beetles. The mischievous turnip- 

 flea is a small beetle, whose larva mines the leaves of the 

 turnip. 



