1 893. J 199 



tenanted only by a single species. In other words, the plants of the 

 two favoured Orders are for the most part many-tenanted, and carry 

 amongst them nearly sixty of our species, whilst those of the nine 

 ill-favoured ones are, with the exception of the elms, single-tenanted, 

 and amongst them all carry but twelve, a very curious and striking 

 contrast. I need, therefore, scarcely observe that it is to the favoured 

 Orders, the Bosacece and Aiiientacece, that the eager collector naturally 

 turns in the expectation of making new discoveries, and it is also 

 among them that so many of his difficulties arise in the endeavour to 

 discriminate between the mines of the different species — difficulties 

 that would be increased tenfold, were it not for the circumstance that 

 each Nepticula, instead of having a plurality of foods as each plant 

 has commonly a plurality of insects, is almost invariably limited to a 

 single food-plant. The following include all the exceptions I am ac- 

 quainted with. Both the nut species, as is well known, are often 

 found on the hornbeam (Carpinus hetulus) ; ceneofasciella is partial to 

 Potentilla tormentilla, in addition to its more usual food, the agrimony 

 (^Agrimonia eupatoria) ; oocyacanihella occurs commonly on apple and 

 pear, as well as hawthorn ; atricolella on apple and hawthorn, but 

 never also on pear, so far as I know ; angulifasciella I have met with 

 in the leaves of Poterium sanguisorha quite often enough for its pre- 

 sence not to be accidental ; but of all troublesome species in this 

 respect nothing can rival the bramble feeder, aiirella : I have little 

 belief in such species as splendidissimella, the Nepticula of the rasp- 

 berry and dewberry, and gei that of the Geum, and in spite of the 

 food-plants would refer both to aurella ; it is also found frequently 

 on strawberry and agrimony, and on one occasion I bred it from a 

 small colony on meadow sweet {Spircea ulmaria), whilst other observers 

 could probably add still further to its dietary. These, perhaps, pretty 

 well exhaust the exceptions among the British species, if we exclude 

 some which feed on the roses, willows and poplars respectively, where 

 the distinctions of the botanist do not appear to be altogether recog- 

 nised by the insects. 



THE EGa. 



By tracing back the mine to its starting point, the egg, or leather 

 its empty shell, can be readily found. It is of good size for such 

 small insects, roundish-oval in outline, moderately domed above and 

 flattened beneath, and of a black or occasionally a brown colour. The 

 colour is due to the presence of frass, for the larva, on hatching, eats 

 its way out through the flat uuder-side straight into the substance of 



S 2 



