As according to Palis and Quiros (2014, p 115-116), Malcolm Knowles outlined some principles and typical characteristics in relation to adult learners:
Like golden clouds in the summertime, the Sulphurs spatter the radiators of our cars and dance over the green fields in happy ecstasy. Not so ecstatic is the farmer who sees voracious green caterpillars eating up his alfalfa and clover. The butterflies are very variable in color with several seasonal forms. The springform is rather pale, but, if you add more orange to the wings, you have the Flavid Sulphur, common in summer. Another summer form has the orange replaced everywhere by lemon yellow. There are several similar appearing Sulphur butterflies, but 3 characteristics in combination usually distinguish the Orange Sulphurs from all others. First, there is a dark diffusion at the base of each wing; second, there are usually 4 or more black dots on the undersides of the wings; and, third, the wings have no pink edges. Albinic or white individuals are quite common.
All over the east, the zebra swallowtail wings its way from blossom to blossom. It is a lover of gardens where it has the habit of lighting on some beautiful flower, then suddenly lifting up and cover a garden wall just as you think you are going to catch it. The strong wings marked indeed like a black and white zebra, but with two red spots like bright rubies near the tail end, carry the butterfly effortlessly clear to the tree-tops.
One day you may see a butterfly land on a leaf or flower near you that has what looks like a long nose sticking away out in front of its face. This is the Snout Butterfly and no other is like it. But forget about the nose, because what looks like a nose is really part of the mouth, the part called the palpi, which are used by an insect to feel food. Somehow the Snout Butterfly uses these very long palpi to detect food it wants to eat. “Maybe,” you would say, “it uses the palpi to help it suck up the food.” This is not likely, as every butterfly has a very long tongue, usually kept curled within the month, which it uncurls to put down in a flower and suck up nectar just as you would suck up soda with a straw.
With the speed of a galloping horse, the great blue Morpho butterfly rushes through the tropical jungle. Faster, far faster, than even the giant swallowtail of North America, the Morpho flies along a dim forest trail. The collector who tries to sweep it into his net is astonished to see the huge blue creature leap up, as he strikes for it, in one great bound that flings it to the very tops of the jungle. The sunlight strikes the myriad tiny prisms of the wings and suddenly the blue is no longer just a blue, but a dazzling glory, a blazing mirror of light so bright it hurts the eyes. A large bird dives for this shining blue prize and equally suddenly the brilliant Morpho disappears, yes disappears completely into thin air.