The explanation of this change is, that Madeira, like many oceanic islands in the temperate zone, is much exposed to sudden gales of wind, and as most of the fertile land is on the coast, insects which flew much would be very liable to be blown out to sea and lost.

Year after year, therefore, those individuals which had shorter wings, or which used them least, were preserved; and thus, in time, terrestrial, wingless, or imperfectly winged races or species have been produced.
That this is the true explanation of this singular fact is proved by much corroborative evidence.

There are some few flower-frequenting insects in Madeira to whom wings are essential, and in these the wings are somewhat larger than in the same species on the mainland.

We thus see that there is no general tendency to the abortion of wings in Madeira, but that it is simply a case of adaptation to new conditions.
Those insects to whom wings were not absolutely essential escaped a serious danger by not using them, and the wings therefore became reduced or were completely lost.

But when they were essential they were enlarged and strengthened, so that the insect could battle against the winds and save itself from destruction at sea.