December 2017

As I write this, the weather has taken a relatively sharp turn as we moved from autumn to winter.   The temperature has dived from a relatively mild 15°C to a decidedly chilly 5-6°C.  This has the effect of driving many of us indoors, venturing out only when fully wrapped.  One insect that also likes to be indoors is the common green lacewing.  The lacewing overwinters as an adult (as opposed to hibernating as an egg or caterpillar) and if it can, it will find a way inside your house where it is warm and cosy and safe from predators.  Once inside your house, a remarkable change takes place – it goes from bright green to a delicate pink colour.  Just why this should happen is unclear – perhaps it is better camouflaged that way despite your choice of décor – but in the spring it will turn back to its natural green colour.  In the wild, lacewings hibernate naturally under leaf litter or in other rough and untidy places you may have in your garden, so perhaps pink is less conspicuous in such places.

Common green lacewing - Chrysoperia carnea

When your lacewing leaves your house in spring it will find a mate and very quickly lay a batch of green eggs.  The eggs also change colour to grey before the emergence, in a few days, of the lacewing larvae.  These are one of nature’s most voracious predators and will eat the larvae and adults of many different species of insect.  Aphids are one of their favourite prey insects and they will chomp their way through a greenfly infestation in very short order.  When I say chomp, that is not quite accurate as they have no biting mouthparts.  Instead, they adopt a similar technique to spiders by injecting their prey with digestive enzymes and sucking out the resultant ‘soup’.  Their appetites make them popular with farmers and gardeners who can buy lacewing eggs as a non-chemical pest control.  (You can even buy them in batches of 1000 from Amazon!)  Once they have cleared your rosebush of greenfly, however, their predatory instincts reduce them to cannibalism until they have eaten enough to spin a cocoon from which the adult insect will emerge.  The entire life cycle takes only about 4 weeks, so that there will be several generations produced before the colder weather drives them in search of a warm winter home.

Common green lacewing (Chrysperia carnea) found in our moth trap

If you want to encourage lacewings to your garden – and with an appetite for aphids like theirs why wouldn’t you? – then you can make a ‘hotel’ for them.  The ‘hotel’ will be similar to the solitary bee hotels that all the garden centres and supermarkets sell nowadays full of short lengths of bamboo for the bees to nest in.  To make one, simply cut the top off a 2 litre plastic bottle (if nothing else it will stop the bottle from ending up in the ocean!), roll up a length of corrugated cardboard and put it inside the bottle so that the ends are protected from rain.  Then hang your hotel in the fork of a tree or under the eaves of your shed, pointing downwards so that water can drain out.  This may attract ladybirds as well as lacewings, a double blow to next year’s aphids.

Here are a few other species of lacewing proving that they are not all green or all that common.

A well marked species found on comfrey. Chrysopa perla

A brown lacewing or Alder Fly, possibly Sialis lutaria

Another species found in the moth trap, possibly Sympherobius elegans

November 2017

My apologies for rattling on about spiders again, but it does seem to have been a particularly good year for our eight-legged friends.  (Of course they are friends, they keep the fly population under control.)  We recently came home to find a garden spider (the one with the white cross on its back) apparently floating in mid-air.  It was, on closer inspection, in the centre of its web, but it was still way above the hedge and surrounding shrubs.  This spider, clearly dissatisfied with the diet obtainable by building a web between shrubs, had climbed the telegraph pole and suspended its web from the telephone wire.  This is as good a demonstration of spider planning and intelligence I’ve ever seen.

Garden Spider

I recently had a trip out to Aberdaron in North Wales where I was struck by the variety of wildflowers still in flower in mid-October.  The trees were starting to lose their leaves there but there was plenty of clover and knapweed in flower.  One particular species stood out - Common Fumitory.  There are only a handful of species of fumitory found in the UK and they are in a very small sub-family called fumariaceae.  I was quite surprised to find that fumariaceae is a sub-family of the poppy family, mainly because of the huge difference in the shape of the flowers.  Apparently they got the name fumitory from the smoke-like appearance of the plant with its grey-green leaves.  It is a certainly a very delicate plant with its fern-like leaves, though I would have called the leaves bright green.  An alternative name for the plant is earth smoke, though to appreciate the smokiness, perhaps you need to get up early when there is dew about and maybe squint a bit. The scientific name for common fumitory is fumaria officinalis.  Plants with officinalis in the name were normally used as herbs or medicines and fumitory is still used by herbalists to treat skin blemishes and conjunctivitis.  Interestingly common fumitory is a source of fumaric acid, which is something human skin produces when exposed to sunlight.  It is also a food additive, often shown in the ingredients list as an acidity regulator and has the E-number E297.  And if you have a taste for salt and vinegar crisps, then the vinegary flavour probably comes from fumaric acid.

Common Fumitory

One consequence of the late flowers is that the insects that depend on nectar are still about and we saw several red admiral butterflies.  This species used to be a migratory species.  Eggs were laid in Southern Europe or North Africa and several generations worked their way northward, arriving in the UK in late spring.  As the weather gets colder in autumn, they then fly south to over-winter and start the cycle again.  But now, with milder winters, there is less pressure to return south and so we now find that some red admirals hibernate here and together with the migrating population swell the total population in the UK.  A sister species of the red admiral is the painted lady which also migrates northwards from Africa and the mystery there was that nobody saw them flying back southwards.  It wasn’t until 2009 that investigations of insects using new radar techniques discovered that they do fly south but at altitudes of over 1000 metres (about 3,300 feet in old money).  The migration(at speeds of up to 30mph in favourable winds) involves a round trip of more than 9,000 miles and six generations of hungry caterpillars. 

Red Admiral

This is a much longer migration than the better known migration of monarch butterflies from Mexico to Canada.  So next time you see a red admiral or a painted lady you can marvel not just at their beauty, but also at just what a tough creature it really is.

Painted Lady