Lunar Hornet Moth

The Lunar Hornet Moth (Sesia bembeciformis) is a day flyer and flies only in July.  Its unusual life cycle begins when the adults emerge from pupae in willow trees in early July.  The female attracts a mate by wafting a pheromone and after mating she lays her eggs on willow bark.  The larvae chew their way into the wood and stay there growing for two years before emerging and the cycle is then complete.

The Lunar Hornet Moth looks, sounds and flies like a hornet or giant wasp.  It is one of a group of clearwing moths that use Batesian mimicry to deter predators, that is they disguise themselves as something more dangerous and unpalatable to a potential predator.

Since 2020 a synthetic pheromone has been commercially available and reports of adult moths have increased dramatically.  This is the third year in a row I have had a go with a lure and all these photos are of males attracted to a pheromone lure in the past week.  (The female moth looks very similar but is larger.)  Once the moths have been in the trap for a few minutes they calm down and are happy to sit on a willow trunk for a few minutes while they gather their thoughts before flying off.

The photos on or in the trap aren't much good so I had a go at flight shots which are tricky but a few came out OK.  This one was taken in natural light and the shutter speed wasn't fast enough to freeze the wing movement.  

These were taken with flash.

For comparison here are a couple of European Hornets (Vespa crabro), also from Gosforth Nature Reserve but a few years ago.  They are brown rather than black but otherwise the moth's mimicry is pretty impressive.

Emperor moths

The Emperor Moth pheromone lure is amazingly potent.  I have tried it out twice this year and each time it produced six male moths within a few minutes.  The first time was at Hepple, west of Rothbury in Northumberland, on the heather moorland near the border with Harwood Forest. The lure is hidden under the bark of a bit of dead wood.  To start with the moths were flapping around like crazy, making it almost impossible to get a photo.  Then one settled on the wood very briefly,

and another landed in the heather nearby and stayed still for several minutes.

A few days later I took the lure to Edmonbyers Common in County Durham.  This was old scruffy heather but the moths arrived within a couple of minutes.  Here you can see three with the pheromone-impregnated lure tucked under the bark.

Here are two fighting to get to the imaginary female.

They are very excited when they arrive but sometimes seem to get tired and just stop for a rest, which makes the photography much easier.  This one stopped on the wood for several minutes, probably exhausted.

It has amazing feathery antennae to pick up the faintest scent of a female.

Eventually I picked it up to be out of the way of the others.  I had taken great care not to get any pheromone on my hands but it was a cold day and the moth seemed happy to be on my warm hand.

I found another rather faded and tattered moth in the grass a metre or so away.

And another worn and tatty individual.

I have yet to see a female Emperor Moth.  She is larger and has the same markings but the background is pale blue-grey, even more beautiful than the pink-brown of the male.

A sheep in wolf's clothing

This is the most impressive example of Batesian mimicry I have seen (= being disguised as something dangerous when you aren't).  Although it is called the Lunar Hornet Moth (Sesia bembeciformis), this looks much more like a giant wasp - hornets are mostly yellow and brown. Indeed, when you see several flying around your head it is difficult not to flinch at first.

Lunar hornet moths are fairly widespread but seldom seen.  Males can, however, be tempted into view with a pheromone lure which mimics the scent of a female moth.  The larvae live in willows and chew their way through the wood for two years before emerging for a brief life as a moth so willows are obviously the best place to find them.

Last weekend I joined Andy Atkinson and the NHSN moth group to look for these moths in Gosforth Nature Reserve.  Andy deployed the pheromone lure and two moths turned up within a few minutes.  As is usually the deal they had to pose for photos before being released.

I already had a lure and trap of my own so the next day I headed for another nearby nature reserve and deployed the lure just upwind of a patch of willows.  Within less than five minutes five or six moths appeared.  Lunar hornet moths are part of a group of clearwing moths and they even fly like wasps so the deception is nearly perfect.  A moth like this would make a tasty snack for a bird but no self-respecting bird would take the risk.  The moths also make a wonderful, very low-pitched thrum as they fly.

The pheromone is in a small vial which sits in a cage under the green lid of the trap. Moths fly under the lid and fall though a yellow funnel into the chamber below, or that's the plan.

Only two moths entered my trap while the others flew around or landed on the roof.

This one is in the lower part of the trap.

I was more interested in just watching them than catching them and belatedly had a go at a few flight shots.  Not easy.

As before, the two in the trap agreed to pose for photos before being released.

It is amazing to be able to summon these moths seemingly out of nowhere.  I think next time I try, probably next year, I'll concentrate on trying to get better photos of them in flight.

The emperor moth

I think this is quite the most beautiful British moth.  This is a male emperor moth, Saturnia pavonia.  It flies in late spring and lives in upland areas.  Males can be enticed into view using a pheromone which mimics the scent of a female.  The males fly in the daytime but the females are said to fly only at night.  I wonder if the females attract males for mating by day but then feed and lay eggs at night.

Just over a week ago I took the pheromone lure, hidden behind the bark of a small log, to Simonside near Rothbury, where I had first seen an emperor last year but this time there was no response.  I moved round to Harwood Forest and within a few minutes a moth appeared.  It flew around incessantly, only pausing for a fraction of a second, so this photo was the best I could do.

On Sunday I went back to Muggleswick in County Durham, which yielded the best photos last year but again drew a blank.  A few miles further south I tried again on the Waskerley Way and a moth arrived within ten minutes.  A few minutes later there were six, all zooming round looking for the non-existent female.  They fly manically so the photography is challenging.  Nearly all the photos are out of focus, or motion-blurred, or miss half the moth, or don't include a moth at all.  Here are a few that turned out OK.

This was the only time I had two in the frame together.

This male discovered the lure and realised it was a con.

The others also disappeared after a few minutes so I moved a few miles west to Horseshoe Hill.  There another four moths arrived to investigate so this seems to be a pretty good area for them.

One of these moths was a bit tatty and looked rather tired with all its exertions and it flopped down onto the grass for a rest so I could even get a photo with the phone.

I had taken great care not to get any trace of pheromone on me or my hands but it did accept the offer of a lift onto my hand for a photo.

My next challenge will be to find and photograph a female emperor but that won't be so easy.

The lunar hornet moth

This is another wonderful day-flying moth that can be attracted to a pheromone lure - the lunar hornet moth (Sesia bembeciformis).  I was privileged to join Andy Atkinson, our local moth expert, to look for this moth in Gosforth Nature Reserve.  It lives in damp areas of willow and sallow so Andy headed for an area of coppiced willow at the edge of the wetland.  The lure comes in a small capsule which is inserted into the top of the trap which is then hung on a branch. Male moths are attracted by the scent and may enter the trap or be netted as they fly around it.

In the second spot Andy tried a moth appeared after a few minutes and was expertly netted.

After release it posed for a photo before flying off.

Moments later there was a second moth, slightly smaller than the first.

It also allowed me a photo after release.

The female moth lays her eggs on the willow bark and the larvae burrow into the wood.  They spend two years eating willow wood before emerging as adults.  Paul Drummond, the reserve warden, showed us a section of coppiced willow containing a lunar hornet tunnel.

This particular larva had not made it to adulthood as it had been predated by a woodpecker.

The lunar hornet moth is one of several similar moths known as "clearwings" that mimic other insects.  It looks more like a queen wasp than a hornet and even flies like a wasp, a very convincing example of Batesian mimicry.  The adult moth may trick the birds into avoiding it but that obviously doesn't always work for the larvae.