December 2014

In December, the television schedules start being padded out with lots of ‘review of the year’ shows, so I’m going to do a quick review of my year.  In April, I set myself a task to record as many species as possible in our own small patch of garden.  As if that wasn’t hard enough, I didn’t want to record anything that I couldn’t photograph – not just for the challenge of doing it, but so that as many as possible could be verified by experts.

Red Wasp - Vespula rufa

As you may be aware, the average garden will contain or be visited by thousands of different species during the year but I have recorded only a fraction of that.  There are many reasons for this, one of the main ones is that wildlife doesn’t generally pose for the camera.  I would have recorded the pair of black redstarts that appeared in the garden a couple of weeks ago.  On 3 occasions they gave me time to get the camera ready, but not enough time to click the shutter, or even frame the shot.  Black redstarts are easy to identify, but a number of small warblers passed through the garden on their way to Africa and even if I was quick enough with the camera, my twitching skills probably wouldn’t have been up to identifying them.  Even things I could identify, like the orange-tip butterfly that I chased round the garden, never landed, so no photograph.  The identification problem means that many groups of species haven’t been recorded.  I know that there are several species of earthworm in the garden, and it would be nice to know which species predominate – I have a book that would help with identification, but it would take a week to study it, and more time digging up worms and I just didn’t get round to it.  There are more subtle reasons that some have escaped identification.  I have recorded about 230 species of moth.  In the main they are easy to identify, but there are several groups that entomologists call gen. det. jobs.  These, in common with many other insects require genital examination to be certain of their species, and that means killing the insect which I wouldn’t do just to satisfy my curiosity.

Another reason for not identifying or photographing species is that they are far too small.  The majority of insect species are less than 3mm long. I would need a good microscope even to see one clearly, and there aren’t many field guides that include anything as small as that.  And I haven’t any chance at all of identifying any of the thousands of species of microbes and fungi that help us with the compost and the fertility of the vegetable patch.

14-spot Ladybird - Propylea quattuordecimpunctata

So having told you a lot of reasons for not recording species, what did I manage to record?  The list includes 231 moths, of which 57 are micro-moths, 12 butterflies, 13 beetles, of which 5 were ladybirds, 7 bumblebees, 3 social wasps, 2 solitary wasps,3 dragonflies, 2 woodlice, 4 spiders, 2 mammals – a rabbit and a brown rat, (the vole and mouse are still unidentified), 60 plants (non-cultivars) of which 4 were grasses, 3 grasshoppers or crickets, 10 hoverflies, 10 shield bugs or capsid bugs, 15 birds, and one species each of slugs, earwigs, harvestmen, robber flies, scorpion flies, sawflies and mayflies.  If my arithmetic is correct (unlikely!) that makes a total of 384 species. 

All the numbers above refer to species and not individuals, of course.  The records have all been lodged with Sussex Wildlife Trust (SWT) using iRecord.  They are available to view, using iRecord (you will need to register with iRecord) by searching for the location ‘Glebe Cottages’.  And Sussex Wildlife Trust would be very happy for you to record your own sightings, I can recommend doing it.  iRecord can be found at www.brc.ac.uk/irecord.

Canary Grass - Phalaris canariensis

Eyed Hawkmoth - Smerinthus ocellata

November 2014

There are 3 species of deciduous oak native to the British Isles – the English or pedunculate oak, the sessile oak, and the turkey oak.  Telling them apart from their leaf shapes alone is difficult, and the most reliable way of separating them is to look at their acorns.  The English oak and the sessile oak have similar acorns, but the English oak acorn has a stalk, whereas the sessile oak acorn doesn’t.  (The word sessile actually means stalkless.)  The turkey oak, on the other hand, has a very distinctive acorn – it has a furry or spiky cup.  If you find yourself face down on the lawn outside the Royal Oak, you may well see such spiky acorn cups.  This shows that whatever its regal connections (I think John Taylor wrote an article a couple of years ago regarding those), the tree outside the Royal Oak  is actually a turkey oak.

Turkey Oak Acorn (Quercus cerris)

Turkey oaks were introduced to the British Isles in 1735, so their ‘native’ status is questionable, but they have a connection with something introduced much more recently.  They play host to a gall wasp that introduced itself from continental Europe around 1950 via the Channel Islands.  Gall wasps, as you probably know, use parts of plants in which to lay their eggs so that when the larvae hatch out, they have a ready source of food and some protection from predators.  Often, the presence of the eggs or larvae, chemically alters the plant’s growth and a gall is formed, which is completely different to the normal form of the plant.  Oak marble galls are probably the most familiar type of gall, they are hard and woody and grow directly on the twigs of the tree.  One of the gall wasps that the turkey oak plays host to (Andricus quercuscalicis) has a relatively complex life cycle.  The female wasp lays her eggs in the male catkins of the turkey oak.  This produces a quite small conical gall that would not be noticed unless you happened to be climbing the tree and specifically looking for it.  But from this gall emerges either the male or the female wasp.  When the males and females have mated, the female wasp has no further interest in the turkey oak.  Her tree of choice is the English oak.  If she can’t find one, then she will settle for a sessile oak, but the English oak seems to be the first choice.  She will then lay her eggs in the developing acorn buds of that tree.  As the acorn grows, it becomes chemically altered by the presence of the wasp egg and larva, and it grows into the most bizarre

Knopper Gall on English Oak

Knopper Gall on English Oak (Quercus robur)

shape, looking more like a piece of popcorn than an acorn.  This type of gall is called a knopper gall – allegedly named after a type of German hat called a knoppe.  On a walk through Hastings Country park recently, we came across a tree that was so infested with knopper galls that there were no normal acorns visible.

The galls fall off the tree in autumn and the following spring, the gall wasps emerge from the knopper galls, but they are all female wasps.  Not only are they female but they are parthenogenic.  This means that they can lay fertile eggs without the help or hindrance of the male.  So they go off and lay their eggs – not on the English oak this time, but on the male catkins of the turkey oak.  And so the process continues with alternate parthenogenic and sexual generations on alternate English and turkey oaks. 

Apparently it is not uncommon for the gall wasps that parasitize oaks to have alternate sexual and parthenogenic generations.   Just what evolutionary pressure has led these gall wasps to lead this strange two-stage lifestyle is unclear, but perhaps it has something to do with other insects that fertilize the oak catkins.  When you start to look at the ‘birds and bees’ in detail, it quickly gets complicated and fascinating – but then isn’t that true of all the natural world? 

October 2014

Wasp damage on Cosmos

A neighbour of mine recently showed me some Cosmos stems that had linear scars along them.  When she told me that it was wasps that had done the damage, I wasn’t particularly surprised being familiar with their habit of chewing up any suitably soft or weathered wood.  I’ve often seen them on fence posts where they chew little grooves along the grain of the wood.  As far as I know, wasps are not into wood carving or marquetry, so what is going on here?  The simple explanation is, of course, that they are making papier maché.  This is not the papier maché that we made out of torn up newspaper and flour paste in school handicraft classes, but a much finer version made out of wood pulp and wasp spit.  Nor are they making model animals or lumpy boxes, but rather the beautiful, intricate and delicate structure of their nest, which includes both the many layered (and therefore insulated) outer shell and the honeycombs inside where the wasp grubs will incubate.

I don’t know what attracts them to Cosmos in particular, but I suspect that it not only provides the wood pulp for their nest, but also because the sap is not far beneath the surface, it also satisfies their sweet tooth.  It is their sweet tooth that also makes them such a nuisance at picnics, and it’s their nuisance value that makes many people want to destroy their nests at every opportunity, whether they are interfering with your gardening or not.  For good reasons why you shouldn’t do that, I can recommend an article written by Steve Backshall in the Daily Mail on that very subject.  And if you have an aversion to reading the Daily Mail, then it is on-line at http://www.dailymail.co.uk/sciencetech/article-2748653/Why-learn-love-WASPS-They-ve-vanished-summer-But-s-shouldn-t-celebrate-writes-STEVE-BACKSHALL.html (or better still just Google Steve Backshall Daily Mail Wasps.)

German Wasp chewing a garden chair

I mentioned the honeycomb structure above, but it has nothing to do with honey, as there is only one British native (introduced) species that stores honey – the honey bee (Apis mellifera).  I was recently asked by a friend how honey bees manage to build such a regular hexagonal structure.  I didn’t know, of course, but I did vaguely remember some research published in the last year or so that provided an explanation.  I found the article which was published as a news item in Nature magazine, as well as the full text of the research paper.  (See http://www.nature.com/news/how-honeycombs-can-build-themselves-1.13398 )  Basically, what happens is that each bee tries to build a circular cell of a particular diameter (6mm) as close as possible to the next bee doing the same thing.  As the cell grows they turn into a series of adjacent cylinders which are heated by the bodies of the wasps which partially melts the wax.  This allows surface tension to pull the wax into a basically hexagonal shape.  (You can show this by creating identically sized bubbles in soapy water, which then form perfectly regular hexagon-shaped bubbles on the surface.  The research team showed it by melting bunches of plastic drinking straws.)  The bees also knead and reinforce the wax to make sure that the walls don’t get too thin.  The result is the perfect hexagon pattern of the honeycomb which has rounded internal corners, no doubt for the comfort of the grubs.

This does leave some questions unanswered though – like how do the bees measure the circle in the first place?  I suspect that this has to do with the fact that all worker honey bees are roughly the same size and they will measure things like we did before we invented rulers and inches.  We had to use measures like cubits (the length of your forearm) and spans (the width of your outstretched hand).  It’s probably got something to do with the size of the bees head.

The next question is – how do wasps make their hexagons with papier maché which doesn’t melt like wax does?  Maybe it’s something to do with surface tension as the paper dries, but the truth is – I haven’t a clue.  It’s still marvellous though.

September 2014

Keeled Skimmer - Orthetrum coerulescens

Earlier this month we went on a walk with Sussex Wildlife Trust looking for Devil’s darning needles and Horse-biters in Ashdown Forest.  And just in case you don’t recognize those old country names for those creatures, we were looking for Damselflies and Dragonflies. (Note that Damselflies are included in the general term Dragonfly, so I shall just use the latter to save words.)  Ashdown Forest, despite its name is mostly open heathland where there are plenty of muddy pools and slow streams that are ideal habitat for those insects.  There are plenty of dragonflies there and for details of the rarities and photos of what we found see www.pettnats.blogspot.co.uk.

You don’t have to go to Ashdown Forest to see dragonflies, of course.  Anybody with a pond, or who lives near anybody with a pond will see plenty of them in their garden at this time of year.  Despite their somewhat sinister country names they are harmless and beautiful creatures that have fascinating life cycles.  (Even the largest Emperor Dragonfly would be unable to break human skin, let alone a horse’s, though you may get a deservedly painful nip should you provoke one enough.)

Blue-tailed Damselflies - in tandem

Their life-cycle starts with a fertilized egg being deposited in or on a reed stem or even just placed under the water by the female.  If you see one dipping her abdomen into the water or crawling backwards down a reed stem into the water, she will be laying eggs.  She will be doing that with or without the ‘help’ of the male.  The male is not helping, he will just be protecting his investment either by clasping her round the neck to prevent another male mating with her, or by flying close by to chase off any males with similar ideas.  

Each male has a pair of claspers on the end of his abdomen that fits with a specially shaped shield just behind the female’s head called a pronotum.  These are connected during mating and any subsequent egg protection behaviour.  Each species has its own special shape of clasper and pronotum which (mostly) prevents inter-species mating.  Specially shaped genitalia or associated equipment is common in the insect world and is often used by entomologists to distinguish between species when other differences are too subtle or too variable.

Emperor Dragonfly - Egg Laying

When the fertilized eggs hatch out, the larvae will skulk about on the bottom of the pond and prey on any smaller invertebrates that they find there and when they get big enough they will even take tadpoles or small fish.  Because they have a hard external skeleton, they have to moult several times in order to grow to their adult size, and they may take two or more years before they are ready to emerge as adults.  The larva will then wait for suitable weather and summer temperatures, before crawling up a reed stem above the water where it splits its external skeleton for one last time and emerges as the adult insect.  It will stretch out its abdomen and thorax and inflate its wings before the skeleton hardens.

Azure Damselflies in the 'Wheel Position'

The adult Dragonfly will then take to the air, feeding on other flying insects and looking for a mate.  Adult dragonflies live only for a few days, or a few weeks at most.  When the male finds a receptive female, he transfers a packet of sperm from the end of his abdomen to the second segment where his ‘equipment’ resides.  As the second segment is near the front, this involves making a complete loop of his abdomen.  He then straightens out and clasps the female behind the head.  She then loops her abdomen round so that the tip connects with the second segment of his abdomen making what is called the ‘wheel’ shape.  They will then either fly in that position, or will find a convenient perch until the fertilization is complete, whereupon the female will detach her abdomen.  They will then either separate completely, or will fly together with the male still clasping the female until the fertilized eggs have been laid.  And then it all starts over again.  It sounds really complicated written down like that, but fortunately dragonflies can’t read so they manage very successfully with what evolution has provided for them.

August 2014

Peppered moth - Biston betularia

National Moth Night turned out to be somewhat damp and so Trevor and I postponed the moth trapping for a week or so and there were plenty of moths out there, including some magnificent hawk-moths, as well as some very much smaller micro-moths that are much more difficult to identify.  One of the difficulties in identifying moths is that some species have several different colour forms, the most famous example of this being the Peppered moth (Biston betularia).  We have Peppered moths in the moth trap quite regularly.  The most common form of this moth is white and it is ‘peppered’ with black dots, but it also has a completely black form.   Originally, most of the moths were the white form, with relatively few of the black form (less than 1%).  But in the nineteenth and early twentieth centuries, it was noticed that most of the moths were of the black form, in fact, by 1895 more than 95% were the black form.  This was because industrial and urban pollution killed the pale coloured lichens, and soot made the trees where they rest during the day, black.  This meant that predators could easily pick out the white form, but the black form was hidden against the black trunk.  Now that we have the Clean Air Act, the lichens have returned and the trees are no longer sooty, so the white form is more common – evolution in action indeed.

Field Grasshopper - Chorthippus brunneus

But moths are not the only creatures with different colour forms.  I recently photographed a pink grasshopper near Dungeness.  I got quite excited when I got back home and read that the pink form of the Meadow Grasshopper (Chorthippus parallelus) was quite a rarity when the normal colour form was green, or green and brown.  When I read a bit further though, I found that some experts think that all the nymphs of the Meadow Grasshopper are pink and that only the females in rare cases retain the pink colour to adulthood.  (Nymphs are the non-flying juvenile form of grasshopper which doesn’t have the larval or caterpillar stage of other insects.)  So of course all I had to do to prove that I had a rarity was to see if the grasshopper I photographed was a nymph or an adult.  I checked and it was indeed an adult, but while I was checking it, I noticed that though it was an adult, it was an adult Field Grasshopper (Chorthippus brunneus).  When I looked up the Field Grasshopper, I found that rather than different colour forms it has a range of colours from buff through green to purple, and that pink wasn’t at all unusual.  Ah well, it’s still a very pretty insect.

Another colour variation you may see if you are anywhere near the Village Hall is a white squirrel.  This is not a different species, but a white form of the Grey Squirrel (Sciurus carolinensis).  There are two reasons why a grey squirrel may be white.  One is albinism, this occurs when the animal has a genetic mutation that makes it unable to produce melanin, which is the substance that gives skin and hair its colour.  The other reason is called leucism and it is where the animal has a normal gene that codes for different fur colours in the same way that we have a gene for blue or brown eyes.  Because the gene is recessive, both parents would have to be white for the offspring to be white.  If one parent was grey then all the offspring would be grey.  The difference between albinism and leucism is that albino squirrels have pink eyes, whereas in leucism they have normal black coloured eyes.  The one by the Village Hall has pink eyes, so it is an albino squirrel.  According to wildlife experts there is a one in 100,000 chance of a grey squirrel being born white.  I've been unable to find out who those experts are, or to find out how they came up with such a suspiciously round number, but it’s a remarkable sight and I’m indebted to Trevor Buttle for the great photograph.

Grey Squirrel - Sciurus carolinensis

July 2014

The house martins have finally settled down and there are two pairs apparently raising two broods of chicks in our eaves.  I say apparently because until the youngsters are big enough to poke their heads out of the nest, it’s hard to tell exactly what’s going on.  But we’ve found several eggshells below the nests and the adults are busy ferrying food into the nests.  Sadly this year, the swallows haven’t nested in the carport.  In fact, the number of swallows seems to be down this year.  I read an article by Bill Oddie in the BBC Wildlife magazine where he recounts his experience of a holiday in Cyprus in the 1980’s when he thought war had broken out due to the number of shotguns being fired.  It turns out that his holiday coincided with the start of the bird shooting season.  He visited again recently hoping that things had improved now that shooting birds was illegal.  It hadn’t.  It seems that people’s liking for ‘sport’ is stronger than the will to enforce the law.  I can’t understand people killing things for pleasure, especially if they are not going to eat their kill afterwards.  I hope that our swallows haven’t suffered that fate, but the evidence seems against it.

In our garden we have Water Figwort (Scrophularia auriculata).  I don’t know why we have Water Figwort as there is certainly no water there and it is in a particularly dry flowerbed.  Part of the reason that we have so much figwort now is that last year I let one Water Figwort flower and set seed.  The figwort has a very strange flower that looks more like something out of a Mickey Mouse cartoon than part of a plant.  In order to set seed, of course, the flower has to be pollinated, and unlike most flowers that get pollinated by bees or hoverflies, the figwort has developed a relationship with wasps.  One species of wasp in particular, the Tree Wasp (Dolichovespula sylvestris), seems to be the main pollinator of the figwort.  Tree Wasps, like many social wasps have a sweet tooth and will take sugar from many sources, from the jam in your picnic, through honeydew from aphids or their own larvae, to nectar from flowers.  However, wasps have very short tongues, probably because they have such large and strong jaws which they use to mash up their meatier prey.  This means that they can only take nectar from flowers that have very short pollen tubes such as figwort, gooseberry or ivy.

Flowers that have ‘wort’ at the end of their name usually had a medicinal use in the days before large pharmaceutical companies thought they could do better.  Of course some of the cures were less effective than others, and one thing that ancient herbalists used to determine which plant to use for which ailment was the Doctrine of Signatures.  Basically, the Doctrine of Signatures meant that plants that had features that resembled parts of the body were used to treat that part of the body, so that for example, Eyebright whose flowers were thought to resemble eyes, was used to treat eye infections.  The only other thing you need to know about Figwort is that fig is an ancient word for piles.  It was thought that the red flower buds and tubercles on the roots of Figwort resembled piles as well as the tubercles on the necks of sufferers of scrofula.  Scrofula was also thought to be cured by the touch of a king or queen, and became known as the King’s Evil as a result.  Scrofula also gives Figwort its scientific name – Scrophularia – as well as to the large family of plants in which it resides, the Scrophulariaceae, which also includes many diverse plants such as mulleins and toadflaxes.

Don’t forget that July 3-5 sees the celebration of National Moth Night (actually 3 nights) organized by Atropos and Butterfly Conservation.  Trevor Buttle and I will be running our moth traps on at least one of the nights, so if you want to see some interesting moths and don’t mind an early start, why not join us to examine the catch.  Send me an email (alan.kenworthy@virgin.net) or contact me through the editor, if you want to know more.

Water Figwort - Scrophularia auriculata

House Martin - Delichon urbica

Tree Wasp - Dolichovespula sylvestris