We had a couple of interesting visitors to our garden this
week – the first was a smooth newt.
Though this may well be a common occurrence in many gardens, it is the
first time I have ever seen one in our garden.
My first thought was that it was on its way downhill to the nearest
standing water, but it turns out that at this time of year it was more likely
to be looking for a damp sheltered place to spend the winter in and ambush
insects from. It was a very small, and
therefore very young newt (less than 2 inches head to tail), so I hope it
wasn’t too put off in its quest by being picked up and photographed. It would have been easy to mistake the newt
for a lizard – they are very much the same shape after all – but if you can get
close enough then the lack of scales on the skin, and the head that looks more
like a frog’s than a snake’s are all the clues you would need. I’d have been equally pleased to see a lizard
though, as we’ve never had one of those in the garden either – so far!
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| Smooth Newt - Lissotriton vulgaris |
The other visitors of note that we had this week were three
female Dark bush-crickets (
Pholidoptera
griseoaptera). These are a quite
chunky dark brown insect with long back legs and long antennae. They are a common insect but I thought it
unusual to see 3 in the garden at the same time. It is
easy to tell the females from the males as the females have a long curved prong
sticking out of their back end. (I could
have re-phrased that in entomology-speak as ‘a long curved ovipositor
projecting from the posterior abdominal segment’, but that would have been
silly.) It is an ovipositor, however,
which she uses to inject her eggs into damp earth or rotting wood. The ovipositor is a common feature of many
insects, but the queen of them all is a species of ichneumon wasp where the
ovipositor is longer than the rest of the insect – and she uses it for the
dastardly purpose of injecting her eggs into other insect larvae deep inside
tree branches or flower buds. The other
interesting ovipositor fact is that the sting of a bee is actually a modified
ovipositor which she uses both for egg-laying and defence, and it is also why
you will never get stung by a male bee or wasp.
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| Dark Bush-cricket - Pholidoptera griseoaptera |
But back to bush-crickets – while I was researching dark
bush-crickets for this column (yes, it does happen!) I came across the
following statement - ‘once the eggs are laid it is 18 months before the
insects emerge, which means that odd-year bush-crickets never meet even-year
bush-crickets.’ I found that extremely
puzzling and I’m still not sure I understand it. Let’s say that our 3 bush-crickets lay their
eggs this autumn. That means that the
nymphs will emerge in the spring of 2017.
They then spend 2 years as a nymph and will become adults in the summer
of 2019, mate and lay eggs in the September of 2019. But the adults that laid their eggs last year
in 2014, will have offspring that mature in the summer of 2018. This would mean not only that the two groups
never mate with each other, but that they are presumably genetically different,
and it makes me wonder how and when it all started, and why we don’t have
bush-crickets one year and then none the next?
I can only assume that such insects evolved when Britain was part of
Pangaea with a tropical climate and blurred seasons, so that the breeding cycle
was more flexible. It may be however,
that some late emerging adults are able to survive the winter and mate with
next year’s generation, but I haven’t been able to find out. There is precious little information on the
internet so I’ll just have to widen the search and see if I can find a
bush-cricket expert.
(I did find an expert and he tells me that the adults don't survive the winter, but the eggs don't stick to a strict 18 month timetable and may emerge earlier or later. This may then affect how long the nymphs take to reach adulthood. This means that the gene pool leaks a little and gets a little mixing between the even-year and odd-year insects.)
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| Swallow Chicks |
We also said goodbye to our summer visitors this week. The swallows that nested in the carport left
as soon as the chicks fledged a few weeks ago, but the house martins seemed to
come and visit their old nest as part of a big flock that gathered on the roofs
of nearby houses before starting their long migration. Of course, it may not have been ‘our’ house
martins at all, it may have just been part of the flock investigating potential
nesting sites for next year, but it’s very easy to get possessive about birds
that have nested with you, even though all you’ve done is to leave them alone. But we’ll wish them Bon Voyage anyway and
hope to welcome them back next spring.
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| House Martin Chicks |
