Well, in this case, we are thoroughly deceived by outward appearances; we are taken in by an identity of structure. In her habits, the Rhynchites of the Sloe has nothing in common with the two with whom she is associated by her classification, which is based solely on the peculiarities of her form. What is more, until she is seen at work, no one would suspect her calling. She exploits the fruit of the sloe exclusively; her grub’s ration is the tiny kernel and its lodging the small stone of the sloe.
So, unskilled in the trade of her fellows, without any change in her tools, the kinswoman of the cigar-makers becomes a driller of caskets; with the same bodkin that serves her relatives for fastening the last layer of a leaf-roll, she hollows a little cup in the surface of a shell hard as ivory. The tool that is able to roll a flexible sheet now wears away the invincible and works like a digger’s pick-axe. And stranger still: when it has finished its arduous piece of carving, it sets up above the egg a little miracle whose exquisite delicacy we shall have occasion to admire.
The grub amazes me no less. It changes its diet. When a denizen of the vine and the poplar, [[159]]it eats a leaf; when a denizen of the sloe, it takes to starchy food. It changes its means of liberation. When they have attained their full growth and the moment comes for them to go underground, the first two have nothing in front of them but a yielding obstacle, the surface layer of the leafy sheath, softened and wasted by decay; the third, like the Nut-weevil, has to pierce a wall of exceptional strength.
What singular contrasts might we not discover in facts of this kind, if we were better-acquainted with the habits of the Rhynchites group? A fourth example is familiar to me (R. Bacchus, Lin.). Identical in shape with the manufacturers of cigars and the exploiters of fruit-stones, worthy, indeed, in all respects of the name of Rhynchites, what does this Weevil do? Does she roll leaves? No. Does she install her grub in the casket of a kernel? No.
Her trade is a very simple one, for her method is confined to inserting her eggs, here, there and everywhere, in the still green flesh of the apricot. Here there is no difficulty to overcome, and consequently no art to be displayed by either mother or grub. The rostrum sinks into a material which offers but a slight resistance; the egg is let down to the bottom of the wound; and that is all. The establishment of the family is a most summary proceeding; it reminds us of the practice of the Larini. [[160]]
The grub, for its part, has no need for talents of any sort. What would it do with them? It feeds on the pulp of the fruit, which soon falls to the ground and is reduced to a jelly. Life is easy in these liquescent surroundings; the infant is bathed in fermenting pap. When the time comes for it to take refuge in the subsoil, the jam-sodden grub has no veil to tear, no wall to break through: the flesh of the apricot has become a pinch of brown dust.
In the old days, the Anthidia,[1] partly weavers of cotton, partly kneaders of resin, set me a difficult problem. Later came the Dung-beetles of the pampas, the Phanæi,[2] some preparing, as preserved foodstuff, cakes of Cow-dung modelled in the shape of a pear, others sausage-meat kept fresh in clay jars. Both suggested the same difficulty: can habits and industries which have no mutual connection be explained as soon as we accept a common origin for these different manufacturers, who moreover are so much alike in conformation? The question crops up again, more urgently, with the four Rhynchites.
That the influence of environment may, to some extent, have caused external modifications; that the light may have accentuated the colouring; that [[161]]the quantity of the food may have brought about some small variation in size; that a warm or cold climate may have thinned or thickened the fur: all these changes and many others besides I willingly concede, if that will give any one any pleasure; but, for pity’s sake, let us take higher ground than this, do not let us reduce the world of the living to a collection of digestive tubes, an assortment of bellies that fill and empty themselves.
Let us reflect upon the masterly touch that sets the whole animal machine in motion; let us question the instincts, the controllers of form; let us remember that glorious expression of the ancients, mens agitat molem; and we shall understand the inextricable difficulty that besets the theorists when they wish to explain how it is that of four insects, as much alike in shape as so many drops of water, two roll leaves, another carves fruit-stones, and the fourth profits by the pulp of a rotten fruit.
If they are affiliated to one another, if they are indeed related, as their so strongly-marked family-resemblance would seem to affirm, which of them was the first of the line? Could it be the leaf-roller?