It almost always comes as a surprise to those uninitiated in ‘The Way of the Moth’ to learn that there are so many day-flying species. Most people, if they think of moths at all, picture a drab, nocturnal insect, which eats their clothes, buzzes annoyingly around lights, or splats onto the car windscreen on summer nights.
Those more enlightened, aware of and delighted by Burnets, Cinnabars, Foresters, Speckled Yellows, Orange Underwings and the rest, know that this is far from true. But even to the most dedicated enthusiast there is one family of day-flying moths which retains an aura of mystery: the clearwings, of which 16 species have been recorded in the UK.
Most day-flying moths in Britain can be seen fairly easily if you know where and when to look; not so the clearwings. With a few exceptions, the chances of coming across them ‘by accident’, even in the right habitat, are extremely low. Perhaps the easiest to find, in southern Britain at least, is the Hornet Moth, which can be found resting on the trunks of Black Poplar after emerging in June and July, but you can look at an awful lot of moth-less poplar trees before you find one!
The odds can be reduced considerably by searching for signs of the moths, such as old emergence holes. All clearwing larvae feed internally in the stems, trunks or roots of various plants, and emerge via these holes. Other signs can include galls or larval excreta (‘frass’). Older moth books frequently contain elaborate instructions for obtaining adult clearwings from such ‘infected’ plants, involving attaching cloth sleeves to branches or sawing lengths off and keeping them in aquarium tanks until they emerge. And until recently, this was the only reliable means of seeing most of them.
Then, about 20 years ago, synthetic clearwing pheromones, which replicate the chemical signals given off by the females to attract males, became commercially available. These quickly revolutionised the business of finding clearwings, and re-drew distribution maps as it was soon realised that many species were a lot more widespread and common than had previously been thought.
The pheromone is usually sold impregnated in a small rubber bung, which is placed in a fine mesh bag tied up with a short string. The bag is hung over vegetation, or simply dropped on the ground amongst the foodplant, and any male moths nearby will hopefully come and investigate. And then quickly go away again when they don’t find a willing female waiting for them!
Using pheromones, it is possible to see almost all the British clearwings, the exceptions being the Lunar Hornet, which doesn’t respond, and the Fiery, which is specially protected and therefore illegal to try and attract in this way.
The moths’ response to pheromones can be immediate and spectacular. Drop the lure into a patch of Bird’s-foot Trefoil on a warm, sunny late morning in June or July, and within seconds there may be half a dozen or more Six-belted Clearwings whizzing around it. After they’ve lost interest, they simply disappear, and I’ve never managed to find one simply by searching amongst the trefoil on hands and knees. It doesn’t always work, though; on other occasions whole days can be spent hanging lures off trees and bushes and standing around waiting with nothing to show for it. Which, it could be argued, only adds to their mystery.
Close up, clearwings are stunning jewels of insects. Mimicking small wasps or flies, they all have various combinations of black, yellow, red or white, usually in stripes, and of course those amazing transparent wings. Under a lens or microscope, a scattering of typical Lepidopteran scales can be seen, but these are not immediately obvious to the naked eye. The only feature that gives them away as moths rather than Hymenoptera is the soft, slightly ‘furry’ abdomen. They even fly like wasps, darting around at high speed with rapid wing beats. If you did happen to see one in flight when you weren’t expecting it, the chances are you would mistake it for something else unless you were really on the ball.
If you’ve never seen a clearwing moth, it’s well worth giving the pheromones a go. They’re not particularly cheap (about £50 for the full set), but local moth groups or recorders may have a set that can be borrowed, or they may arrange outings specifically to look for them. The lures are available in early spring each year from Anglian Lepidopterist Supplies – a completely unsolicited recommendation, by the way!
To whet your appetite further, photos of all the British species can be seen on Ian Kimber’s excellent UK Moths site.
All images copyright Andrew Mackay.