Page:Popular Science Monthly Volume 26.djvu/192

180 contact with the ripe summit of the seed-vessel, on which he rubs the pollen from the last spike he visited; and then, proceeding downward, he unconsciously collects a fresh lot to carry away to the next figwort. Of course, the wasp himself is not in the least interested in these domestic arrangements of the plant whose honey he seeks; all he wants is his dinner, but in getting it he is compelled, without at all suspecting it, to act as carrier for the fig-wort from one spike to another.

Wasps are remarkably sharp and wide-awake insects; and it would be very difficult indeed to take them in. Flowers that bid for their attentions must provide real honey, and plenty of it. It is quite otherwise, however, with flies. Those mixed feeders are the stupidest and most gullible of all insects; and many unprincipled blossoms have governed themselves accordingly, and deliberately laid themselves out to deceive the poor foolish creatures by false appearances. On most mountain bogs in Britain one can still find a few pretty white flowers of the rare and curious Grass of Parnassus, They have each five snowy petals, and at the base of every petal stands a little forked organ, with eight or nine thread-like points, terminated, apparently, by a small round drop of pellucid honey. Touch one of the drops with your finger, and, lo! you will find it is a solid ball or gland. The flower, in fact, is only playing at producing honey. Yet so easily are the flies for whom it caters taken in by a showy advertisement, that not only will they light on the blossoms and try most industriously for a long time together to extract a little honey from the dry bulbs, but even after they have been compelled to give up the attempt as vain they will light again upon a second flower, and go through the whole performance again, da capo. The Grass of Parnassus thus generally manages to get its flowers fertilized with no expenditure of honey at all on its own part. Still, it is not a wholly and hopelessly abandoned flower, like some others, for it does really secrete a little genuine honey quite away from the sham drops, though to an extent entirely incommensurate with the pretended display.

Most of the flowers specially affected by carrion-flies have a lurid red color, and a distinct smell of bad meat. Few of them, however, are quite so cruel in their habits as Rafilesia. For the most part, they attract the insects by their appearance and odor, but reward their services with a little honey and other allurements. This is the case with the curious English fly-orchid, whose dull purple lip is covered with tiny drops of nectar, licked off by the fertilizing flies. The very malodorous carrion-flowers (or Stapelias) are visited by blue-bottles and flesh-flies, while an allied form actually sets a trap for the fly's proboscis, which catches the insect by its hairs, and compels him to give a sharp pull in order to free himself: this pull dislodges the pollen, and so secures the desired cross-fertilization. The Alpine butterwort sets a somewhat similar gin so vigorously that when a weak fly is caught