Saturday, 20 October 2012

A year in mothing

It's now been a year since I moved into my house in central Bedfordshire. Within a few days I'd unpacked the moth trap and started populating my garden list. Early catches were promising, including the first Autumnal Rustics I'd ever seen, and the spectacular Merveille-du-jour.

Autumnal Rustic - 2117
Autumnal Rustic
Merveille du jour - 2247
The marvellous Merveille-du-jour

With the new year came an added incentive to trap, in the form of a mothing competition with several friends. The rules are simple, whoever can catch the most species of macro-moth in their garden in a year would be crowned the victor. Having trapped in a fairly haphazard fashion in my previous garden, I was unsure as to what a good score would be, but 100 seemed like an achievable target.

The year started well, with classic early year moths such as Spring Usher, Oak Beauty, and even better the locally scarce Small Brindled Beauty. As march progressed the total was ticking steadily along, but then came the wettest April record, and astonishingly, a blank month.

Oak Beauty - 1930
Oak Beauty

May and June weren't much better, but in the dry patches some good moths were tempted into the garden, including only the 23rd Bedfordshire record of Chamomile Shark.

Chamomile Shark - 2214
Coxcomb Prominent
Mohican moths, Chamomile Shark (top) and Coxcomb Prominent (bottom)

Things really picked up in late July, with one balmy evening producing an impressive 48 species, including the remarkable Leopard Moth and Drinker.

Leopard Moth
Two of the more odd looking moths caught this year Leopard (top) and Drinker (bottom)

The total continued to climb through August, breaking first the 100 barrier, then powering past 150. with several moths I'd never seen before, such as Scorched Carpet and the locally scarce Webb's Wainscot.

Scorched Carpet
Scorched Carpet
Webb's Wainscot
Webb's Wainscot

Fast forward to October, and the competition has narrowed to a two horse race, with both trappers locked at 184 species each. Surprisingly the two lists differ by 30+ species, showing just how diverse moths are in this country. Several species caught last year are yet to make an appearance, in particular Autumnal Rustics have been notable by their absence; although given that the species has declined by over 90% in recent years, perhaps that's not surprising.

I've certainly enjoyed the added spice the competitive element has brought, I never thought the arrival of the first common marbled carpet of the year would bring so much excitement! Hopefully the pictures in this post show how remarkable and attractive moths in the UK can be, and might tempt one or two people to get involved themselves, I thoroughly recommend it!

Wednesday, 5 September 2012


Many of the insect species that occur in the UK are liars. Perhaps not liars in the conventional sense, but liars in the messages they send through their appearance. Species which are completely harmless dress themselves up with the bright warning colours of more dangerous species to warn off potential predators. This kind of deception, where a harmless species copies the patterning of a toxic or dangerous one, is known as Batesian mimicry, and is widespread across the natural world.

One group of insects which is more dishonest than most is the hoverfly family, with the majority of the species in the UK pretending to be something they're not. One of the commonest targets for mimicry are the social wasps, who advertise their powerful stings with bold yellow and black marking and consequently are left well along by most predators.

To human eyes the accuracy of the imitation varies significantly, have a look at the picture of a common wasp below and see how well you think the hoverflies beneath it have done in their attempts to copy it.
Common Wasp
Chrysotoxum cautum
Chrysotoxum cautum, not a bad effort
Myathropa florea
The Dead Head fly Myathropa florea, another strong contender
Xanthogramma pedissequum
Xanthogramma pedissequum, perhaps a bit too jazzy?
Helophilus pendulus (m)
The Sun-fly Helophilus pendulus, going freestyle on the thorax

As you can see from just the four examples above, there is a huge amount of variation even amongst species attempting to copy the same template. Why is this? Surely to garner the greatest protection, the mimic should have evolved near perfect imitation of the target species? Various hypotheses have been suggested, perhaps to non-human eyes the imitation is more exact, or maybe evolution is still in progress. Another suggestion is that some species may display elements of several different target species to maximise their protection. In most cases a combination of the above and other factors are likely to play a part.

Whatever the reason for imperfect mimicry, there are some species which show a very good similarity to their targets, a small selection is shown below.

Honey Bee
Eristalis tenax
A Honey Bee and a Drone Fly
Volucella bombylans
Common Carder Bee
The bumblebee mimicking hoverfly Volucella bombylans and the Common Carder Bee
Volucella zonaria
A Hornet and a Hornet Hoverfly, although the differences may be readily apparent in the stationary insects, in flight they are remarkably similar.

Monday, 27 August 2012

In Praise of Ragwort

Ragwort doesn't have a great reputation, it is one of just five species of plants listed as an "injurious weed" in the UK, chiefly due to its toxicity to horses and cattle. The toxicity comes from a cocktail of chemicals called alkaloids, which if consumed in large quantities can cause severe liver damage to mammals. The alkaloids are toxic to most insects as well, but there are some thirty species which can not only tolerate consuming ragwort, but are entirely reliant upon it.

Undoubtedly the most common and widespread of these species is the cinnabar moth, whose caterpillars can  reliably be found on almost any decent stand of ragwort. Turning the plant's defences to their own purposes, the caterpillars incorporate the toxins into their own bodies, and then advertise their distastefulness with bold orange and black stripes. 

Cinnabar caterpillars
Cinnabar caterpillars munching their way through ragwort

Cinnabar Caterpillar
Close-up of a single cinnabar caterpillar

The adults are equally toxic, and even bolder in their advertisement, going for the classic warning colours of red and black. The sight of an adult moth bursting out of the undergrowth in a blaze of colour often leads to people searching through their butterfly books for a bright red or pink species.
Cinnabar - 2069
Adult Cinnabar moth

In addition to the specialist species, some of which are extremely rare, there are a host of species for which ragwort provides an invaluable source of pollen and nectar, especially in the wasteground areas which it frequently occupies. At this time of year ragwort is the first plant I head to when looking for interesting insects.

One of my favourites is the mining bee Colletes fodiens, another species lacking an English name, perhaps it could be the ragwort bee? Although not entirely reliant on ragwort, I seldom see it on any other flower. Superficially resembling a small bright honeybee, the broad white stripes on the abdomen instantly distinguish it as a Colletes species, although separation from the other Colletes species is somewhat trickier, see here for some further information.

Colletes fodiens
Colletes fodiens foraging on Ragwort

On any given day there are over a hundred other species which could be found on ragwort, below is just a small selection of the variety of life supported by this one "injurious weed". There is no doubt that ragwort can cause problems when in the wrong place, but in the vast majority of cases it is a extremely valuable component of the British countryside, and one which deserves a better reputation than it currently possesses.

Meadow Brown
A common sight of the British summer, a Meadow Brown

The Forester - 163The striking Forester Moth, now a somewhat scarce and declining species

Antler Moth - 2176
The attractively patterned Antler Moth

Syrphus ribesii
A classic hoverfly, Syrphus ribesii

Red-tailed Bumblebee
A red-tailed bumblebee, one of several bumblebee species to be found on ragwort

Stictopleurus punctatonervosus
Stictopleurus punctatonervosus, a recent colonist to much of the UK

Tuesday, 21 August 2012

Insect of the week #1 Eristalis intricarius

Flowering Buddleias, or butterfly bushes, are everywhere at the moment and Peacock and Red Admiral butterflies are taking full advantage.

Red Admiral

In another year, they'd be joined by Painted Ladies, but they seem thin on the ground, especially compared to the record breaking summer of 2010, when millions descended on the UK.

Painted Lady

Compared to these gaudiest of insects, the bees and hoverflies which come to share the buddleia bounty would be easy to ignore, but many are worth a closer look.

Take for example the hoverfly Eristalis intricarius. Like so many British insects it lacks a common name, suggestions welcome! All the other Eristalis species are mimics of honeybees, indeed a quick look at a buddleia will almost certainly reveal at least one of them. Intricarius goes for mimickry on a grander scale, sporting the furry coat and colouration of a bumblebee.

Eristalis intricarius

Females are decked out with the furry body and white tail of a classic bumblebee, whilst males go for a natty ginger tail.

Eristalis intricarius

Intricarius is a widespread hoverfly, turning up in a variety of habitats, on a range of flowers, including the ubiquitous garden buddleia. So next time you're passing a butterfly bush, try looking past the gaudy show-offs and see if you can spot a hoverfly in a furry coat!