EGGLAYING OF BUTTERFLIES. 3 



and it is further observed how important this is to the insect, for 

 should they lay them a fraction of an inch higher up, they would 

 almost certainly be destroyed, as, when the buds once open, the petals 

 are very easily blown away by the wind. Similarly it is noted 

 (op. cit., xii., p. 269) that, when the ? s of the late brood of this 

 species lay their eggs on the ivy-umbels, the base of the calyx is also 

 almost always chosen. It is remarkable that, if the twigs are chosen 

 instead of the flowers, the eggs are laid much more indiscriminately. 

 In the same manner both the 2 s of the early brood of this species, and 

 of Callophrys rubi, frequently choose Bhamnus frangula, and, when this 

 is so, the base of the calyx appears again to be almost invariably chosen. 

 Similarly, the eggs of Nemeobius lueina are laid on the undersides of 

 primrose leaves, generally one on each leaf, but two, three, four or 

 even five are sometimes to be found on the underside of the same leaf, 

 possibly laid by different ? s, but it is the underside and not the upper- 

 side of the leaf that is practically always chosen. As we propose 

 giving a separate paragraph on the mode of egglaying of each of our 

 British species in the systematic part of this work, there is no need to 

 give a large number of examples here. 



One of the most remarkable facts connected with the egglaying of 

 butterflies is what may be termed the botanical instinct. Species 

 whose larvae are usually confined to one or two plants will sometimes, 

 under the stress of necessity, select an introduced plant, and it is 

 remarkable that, in most cases, this will be a plant closely allied 

 botanically to its natural foods. The $ Euchloe cardamines chooses the 

 base of the footstalk of a somewhat -passe flower of Cardamine jiratensis 

 on which to lay its yellow egg. Failing this it will accept Alliaria 

 officinalis, and other common Cruciferae, and, if it enters a kitchen- 

 garden will utilise the flowers of horse-radish. Never by any chance 

 does it select any plant unless it belongs to this natural order. 

 Similarly the 5 s of Gonepteryx rhamni choose the underside of the 

 leaf of a Rhamnus bush, laying the egg on one of the veins, and passing 

 by all other plants in the hedge or woodside, however similar they 

 may appear. This selection appears to be made by the sense of smell, 

 and the accuracy with which the selection is made is sometimes very 

 remarkable. Fritz Miiller cites some curious instances in which 

 butterflies appear to have recognised the affinities of certain plants 

 before they had been discovered by botanists, e.g., he says (Nature, 

 xxx., p. 240) : " The caterpillars of Mechanitis, Dircenna, Ceratinia and 

 lthomia, feed on different species of solanaceous plants (Solanum, 

 Cyphomandra, Bassovia, Oestrum), those of the allied genus Thyridia on 

 Brunfelsia. Now this latter genus of plants had been placed unanimously 

 by botanists among the Scrophidariaceae, until, quite recently, it was 

 transferred by Bentham and Hooker to the Solanaceae. It thus appears 

 that butterflies recognised the true affinity of Brunfelsia long before 

 botanists did so. Another and more curious instance of butterflies 

 confirming the arrangement of plants in the Genera Plantarum is 

 exemplified by Ageronia and Didonis, which were formerly widely 

 separated by lepidopterists, being even considered as belonging to 

 distinct families, but now placed near each other in the Nymphalids, 

 the larvae leaving no doubt of their close affinity. The larvae of 

 Ageronia feed on Dalechampia, those of Didonis on Tragia. These two 

 euphorbiaceous genera were widely separated by Endlicher, who placed 



