COLEOPTERA 187 



violaceus creeping about the inflorescences of an Umbellifer (Aegopodium Podagraria), 

 obviously pursuing other visitors. 



Considering the small importance of beetles with regard to pollination, continues 

 Herm. Miiller (op. cit., p. 34), it is scarcely worth while to compare all the antho- 

 philous species, genera, and families with their nearest non-anthophilous relatives 

 in order to discover any possible adaptations to flowers. It will be sufficient to 

 investigate one family — the Cerambycidae — with this object. 



One of the chief groups of this family, the Lepturidae, includes our native 

 genera Rhamnusium, Rhagium, Toxotus, Pachyta, Strangalia, Leptura, and Gram- 

 moptera. The large majority of species belonging to these genera are exclusively 

 anthophilous when adult, except those of Rhamnusium, which are never seen upon 

 flowers, but only on willows and poplars. The species of Rhagium are found chiefly 

 on fallen wood, but now and then on flowers ; those of Toxotus mostly occur on 

 flowers, more rarely on shrubs ; and the species of the four remaining genera 

 confine themselves entirely to flowers. Pari passu with increasing predilection for 

 flower-food are developed those peculiarities in bodily structure which distinguish 

 Lepturidae from other Cerambycidae, and which enable them to feed on exposed 

 or more deeply seated nectar. The characters in question are : elongation of the 

 head forward ; a neck-like constriction behind the eyes, giving the power of directing 

 the mouth to the front ; elongation and anterior narrowing of the prothorax ; and 

 the development upon the lobes of the maxilla of hairs used to lick up nectar 

 (Fig. 76). 



All these characters present a complete series of adaptational stages, from those 

 Cerambycidae which never visit flowers, and those which can only lick tolerably 

 exposed nectar, up to Strangalia attenuata, which is able to extract nectar from 

 the bottom of the corolla-tubes of Knautia arvensis that are 4-6 mm. long. 



In concluding his account Herm. Miiller remarks that, ' although the 

 Coleoptera are of little importance for the pollination of our native flowers, they 

 are nevertheless of special interest. This is because they show very clearly the 

 first beginnings of insect anthophily, and the early adaptations correlated therewith. 

 We see that among the most diverse coleopterous families, of which the members 

 vary greally as to their diet, individual species have first partly and then entirely 

 accustomed themselves to flower-food, with the result that variations favourable to 

 this habit have been naturally selected. Transition to the anthophilous habit must 

 in some cases have taken place long ago, in other cases more recently, for we 

 find on the one hand that sufficient time has elapsed for the evolution of antho- 

 philous genera and families — by adaptational divergence — while on the other hand 

 we find anthophilous species side by side with sister species that have no taste 

 for flower-food.' 



These details of coleopterous structure as described and luminously expounded 

 by Hermann Miiller, apply only to our indigenous species. As he himself remarks 

 ('Fertilisation,' p. 433, note), 'Some tropical and sub-tropical beetles present much 

 more thorough adaptation to flower-food. Thus, in a species of Nemognatha, which 

 my brother Fritz MuUer observed sucking flowers of Convolvulus at Itajaky [m 

 South Brazil], the outer maxillary lobes (galeae) are modified into sharp grooved 

 bristles (12 mm. long), which when apposed form a suctorial tube like the proboscis 



