OTHER LEAF-ROLLERS
Is the insect’s trade determined by the nature of the tools of which it disposes, or, on the contrary, is it independent of them? Does the organic structure govern the instincts, or do the insect’s various aptitudes hark back to origins that cannot be explained merely by the details of its anatomy? We shall obtain an answer to these questions from two other leaf-rollers, the Apoderus of the Hazel (A. coryli, Lin.) and the Attelabus (A. curculionoides, Lin.), both of them eager rivals of the cigar-makers who work the poplar and the vine.
According to the Greek lexicon, the term Apoderus ought to mean ‘the flayed.’ Is this really what the author of the expression had in mind? My few books, the odd volumes of a village naturalist, do not enable me to reply. However, to me the word is explained by the insect’s colour.
The Apoderus is a skinless creature, displaying its naked and bleeding misery. Its colour is vermilion, as bright as sealing-wax. It is like a drop of arterial blood coagulated on the dark green of a leaf.
To this loud costume, rare among insects, are [[141]]added other, equally unusual characteristics. The Weevils are all microcephalous. This one exaggerates the absurd disproportion even further: she retains only the indispensable minimum of a head, as though she were trying to do without one altogether. The cranium in which her poor brain is lodged is a paltry, glittering, jet-black speck. In front of this speck is no beak, but a very short, wide snout; behind is an unsightly neck, which one might imagine to have been strangled in a halter.
Standing high on her legs, clumsy in her gait, she ambles step by step across her leaf, which she pierces with round windows. The material removed is her food. Faith, a strange creature: a reminiscence, maybe, of some ancient mould, cast aside by life’s progress!
Three Apoderi and no more figure in the European fauna. The best-known is that of the hazel. This is the one to whom I propose to devote my attention. I find her here, not on the hazel, her lawful domain, but on the common alder. This change in her activities deserves a brief investigation.
My district does not suit the hazel very well; the climate is unfavourable, being too hot and dry. On the high slopes of Mont Ventoux it grows sparsely; in the plain, except in the gardens where a few find a footing, they are no longer to be seen. In the absence of the fostering bush, [[142]]the insect, without becoming impossible, is at least extremely rare.
Long though I have been beating the brambles of my countryside over an umbrella held upside down, here is our Apoderus for the first time. For three springs in succession I see the red Weevil on the alder and observe her work. One tree, one alone and always the same, in the osier-beds of the Aygues provides me with this leaf-roller, whom I now for the first time see alive. The other alders round about have not a trace of her, though they are only a few yards distant. There is here, on this privileged tree, a small, accidental colony, a settlement of foreigners, who are becoming acclimatized before extending their domain.
How did they come here? Undoubtedly brought by the torrent. The geographers call the Aygues a water-course. As an eye-witness, I should call it, more accurately, a pebble-course. Understand me: I do not mean that the dry pebbles flow down it of themselves; the low gradient does not permit of such an avalanche. But only let it rain; and they will stream fast enough. Then I can hear the roar of the grinding stones from my house, a mile and a quarter distant.