Flying high: A hoverfly attempting a landing. (Source: Ranjit Lal)
When you watch YouTube videos of views from the cockpit of commercial airliners landing or taking off, you’re gobsmacked by how complex it all seems. And yet, everything seems to happen in slow motion as the giant plane drifts lower and lower, and, finally, touches down, with the commander and first officer looking as cool as if they were at some club relaxing by the pool. It’s made me wonder what the cockpit eye-view would be for insects doing the same thing and what must be going through their little brains as they go in for a landing or prepare to take off (often in one hell of an emergency as your hand whooshes down to swat them!).
Butterflies and moths with their big wings frankly seem far too drunk to be allowed up in the air. Surely everything they see must be jerking madly in every direction as they teeter in for a landing. How do they orient? Like other insects, they first seem to circle around their chosen bloom, gradually homing in on it, before hovering just over it with their legs extended — ready to make first contact. Often, they will land and keep fluttering their wings before deciding if it’s safe to switch off engines, as it were, and that there’s no need to abort and do a “go-around”. Now they’ll fold their lovely wings together over their bodies or slowly flap them open and shut, or spread them open to soak in some sun. Then, out unravels the long watch-spring proboscis and refueling with nectar begins, before the next flight out. If you closely watch a large moth take off you might notice a shower of fine dust blowing off its wings: those are scales (butterflies have them, too: that’s the fine powder left on your fingers after you handle them) and they’re said to assist the aerodynamic efficiency of the wings.
Most other insects, however, like flies, bees, wasps and dragonflies don’t have scales on their wings. Their lovely transparent wings comprise two layers of chitin sandwiched together by a strong network of veins and, like cellophane, can bend and twist every which way in order to create the little lift-providing tornadoes (called vortices) required for flight. But bees and wasps, too, seem to swirl around their landing spots, gradually coming in closer as they finally touch down and settle. Some flowers are exceedingly helpful and provide “runway lights” as it were in the form of ultraviolet guide patterns on their petals. The flowers have their own vested interest — the landing bee or hoverfly has to refuel and pick up a load of pollen to be deposited at its next destination — and, maybe, drop off whatever pollen it is already carrying.
As insects are cold-blooded they have got to warm up their engines to at least above 25 degree Celsius before take-off. This forms part of their pre-flight procedure. Some are capable of whirring their flight muscles after disengaging their wings, as you might rev your car engine to warm it, while keeping it in neutral. Conversely, bees are known to use their wings as fans to cool down overheated hives.
While most insects started off by having two pairs of wings, they soon realised that just a single pair was more efficient and easier to control. Only a few insects, like dragonflies and mayflies still use four wings for flight — which they can beat independently of each other. These are controlled by two pairs of flight muscles in the thorax, each pair powering a down-stroke and an up-stroke respectively. In many other insects, the four wings are hitched together, either with hooks or zips, to effectively form a single pair — as in butterflies. In other insects, one pair of wings evolved into stub-like halteres, which worked like gyroscopes and helped in orientation. In the big, bumbling beetles (like the blister beetle, for example), which frankly seem to have very little directional control while flying, the forewings developed into hard waxy “elytra” or wing cases — they extended up at a 45-degree angle in flight, slightly assisting in lift. Mosquitoes have perfected the art of night flying — landing and taking off with pin-point accuracy in pitch darkness. They sense body heat and carbon-dioxide, and, somehow, touch down on a juicy earlobe.
How, for that matter, do flies manage to land upside down on the ceiling? Actually it’s very simple. Compared to us, they see things in slow motion (which is why they dodge so easily), so as they drift up to the ceiling, they raise their heads and front legs up (aircraft would stall at the angles if they do this) till they’re perpendicular to the ceiling, reach out to touch down with their front legs and complete a neat handstand to finish the landing!
But what still boggles the mind is, how those tiny hoverflies suspend themselves in midair and zip in all directions in a millisecond before “standing still” again in a beam of sunlight. What is their cockpit-eye view when they do this? Makes you dizzy just thinking about it!