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.
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| 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.
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| 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.
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| A well marked species found on comfrey. Chrysopa perla |
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| A brown lacewing or Alder Fly, possibly Sialis lutaria |
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| Another species found in the moth trap, possibly Sympherobius elegans |
