Very small insects

Posted by John Blatchford Feb 28, 2007

Fairyflies can be extremely tiny (see my article on Greenhouse Thrips), and their world must be very different from the one we know. Some species are smaller than a few of the single-celled organisms that exist today, and the mystery for me is how they manage to have such minute structures. Fairyflies have all the usual insect parts (digestive system, muscles etc.) and these are all composed of many cells – how they manage to have functional cells of this size?

When it comes to their physical environment things become weird. For such small creatures the differences between the viscosities of air and water are small. For them the air must feel like a thick soup! – with water just a little bit thicker. It is true that they have wings, but these are used much more to ‘catch’ the air than to actually fly through it. They drift on air currents much like baby spiders who use a silk thread to help ‘catch’ the wind.

Flying through water might even be easier. Water (in an aquarium or pond for example) can often be remarkably still. Under these conditions Fairyflies that parasitise water creatures can flap their wings and fly quite effectively. What I do not understand is how they manage to move from air to water. The surface tension at the water/air interface must be enormous for them. Perhaps they cannot cross this barrier ‘on their own’? Maybe they can only move from air to water when they are inside their (much larger) hosts?

These are just a few of the things that I cannot understand about very small creatures. If any reader knows some of the answers I would be very grateful! (Enter the discussion)