This was communicated by Mr. Wakefield in a letter to Mr. John Curtis, the substance of which was read before the Linnean Society in 1854, and published in their Proceedings (see Proceedings of the Linnean Society, ii. 293), where we read: "He (Mr. Wakefield) states that he has seen the black species (_Formica nigra_, L.) for days and nights together industriously occupied in dragging to its cells the seeds of the common violet (_Viola odorata_, L.)
"He first noticed this fact on the 3rd of July, 1832; and he regards it as a curious subject of inquiry for what purpose, if not for their own future provision, they could accumulate these stores?" Mr. Wakefield appears to accept this as evidence that these ants possess the habit of storing seeds; but this is not so, as will be seen by reference to my note alluded to above, and I am inclined to believe that they collect these particular seeds either under the mistaken belief that they are larvæ, to which when fresh they bear some resemblance, or for the sake of some juices which they may obtain from the fleshy appendage attached to the seed.]
[Footnote 111: Six other species belonging to the genus _Atta_ are found in Europe, but they are all unknown to me.
It seems likely that, if other harvesting ants do exist in Europe they may belong to one of these six species; for we have seen (_Ants and Spiders_, p. 59) that all the ants which are known to possess this habit are either members of the genus _Atta_ or belong to genera closely related to it.]
In the case of _Pheidole megacephala_ (the only other European ant which I have detected collecting seeds in large numbers), I have never been able to find granaries or subterranean stores of any kind, though I have frequently made extensive search for them, and explored, to all appearance, the whole nest.
When we remember the great variety of ants which inhabit Europe alone (a recent list[112] enumerating no fewer than 104 distinct species), it certainly may seem strange at first that only two of their number should possess this habit. Perhaps, however, we may yet discover that some other of these species are true harvesters; but at present the chances seem rather against it, since the harvesters found at such distant points as Algiers, Cadenabbia, and Montpellier have all turned out to belong to one or other of the two species, _structor_ or _barbara_.