NEPTICULA GRATIOSELLA. 255 



track, with a blackish-brown line of excrement, which does not touch 

 the margins of the mine, and then gradually expands into a very 

 broad and long gallery, or an elongate, irregular blotch, which some- 

 times overlaps and includes the original slender tracks. The broader 

 part of the mine is yellowish, intersected by the rather slender wavy 

 line of excrement (Frey). Wood writes : " The mine of N. gratiosella 

 varies according to the position in which the egg is laid, and to some 

 extent also according to the size and fleshiness of the leaf. The 

 favourite spot for the egg is underneath the leafy frill edging the stalk. 

 When laid here, the mine travels at first for a short distance down 

 the stalk, it then turns round and proceeds in the opposite direction, 

 till it reaches the blade ; here it keeps accurately to the edge for some 

 little way, and then makes one short turn back upon itself and ends, 

 or, if the leaf be especially large and fleshy, the last turn is omitted. 

 This form would be quite sui generis, were it not occasionally mimicked 

 to a turn by that of A T . pygmaeella, still, as the one larva is green and 

 the other yellow, there is no risk of confusing the full mines ; whilst 

 the empty ones may be told from the position of the eggs. Sometimes, 

 instead of a single turn back upon itself, two or three are made if the 

 leaf be small and thin, yet for all that, the mine is so small tbat it 

 manages to keep within the limits of the lobe. The other position for 

 the egg is under one of the ribs. In this case the small twisting 

 gallery keeps within a narrow compass in the middle of the leaf or in 

 one of the lobes." 



Larva.— The head of the larva is of the palest brown, so that little 

 more than the mouth-parts are visible in the mine. There is no trace 

 of the cephalic ganglia. The ground-colour is green, inclining to 

 bluish-green (not " yellow," as described by Stainton in the Manual), 

 oxyacanthella-like. Frey noticed, in the Linn. Ent., xii., p. 430, that 

 this was not one of the " yellow " larvae of the hawthorn. 



Comparison of mine and larva of N. gratiosella with those 

 of N. oxyacanthella. — The eggs of both species are laid on the under- 

 side of the leaf, but whilst A T . gratiosella prefers the stalk to a rib, 

 N. oxyacanthella has a greater liking for the ribs. The mines are very 

 similar, but that of N. gratiosella is smaller, the gyrations shorter and 

 keeping close together, whereas in N. oxyacanthella the curves are 

 sweeping, and pass across or round the lobes from one side of the leaf 

 to the other, and even when the egg is laid upon the stalk, and the 

 mine comes out along the edge as in N. gratiosella, it turns off sooner 

 or later into the body of the leaf, and pursues its usual bold and 

 wandering course. The best distinction, however, lies in the larvae. 

 The head of that of N. gratiosella is of the palest brown, so that little 

 more than the mouth-parts are visible in the mine ; that of N. 

 oxyacanthella is grey or black, and is always distinct and sometimes 

 very distinct ; N. oxyacanthella also shows, but obscurely, the cephalic 

 ganglia, of which there is no trace in the other. I think, too, that 

 the ground-colour is more bluish in the larva of N. gratiosella than in 

 that of N. oxyacanthella. . . In Herefordshire, both species are single- 

 brooded. I never find the larva of A 7 , oxyacanthella in July and 

 August, nor that of A r . gratiosella in September and October, and I 

 have given the hawthorn hedges a good deal of attention (Wood). 

 The mine is recognisable from its " grey " appearance and " brown " 

 excrement (Threlfall). 



