Our bath acts as a giant pitfall trap for spiders, woodlice
and silverfish that often become trapped when they come to drink from a
dripping tap, but this was the first weevil that has fallen in.
At first, I thought it was dead, laying on its back with
legs in the air but it was performing thanatosis - the strange behaviour of
some animals that pretend to be dead when they are threatened. It’s also known
as ‘playing possum’, because the most famous exponent is the Virginia opossum,
but many other animals do it, from grass snakes to tiny insects..
This particular individual seemed to have had a close
encounter with a spider’s web and was wearing some of it like a silken vest.
The adult vine weevil is a slow-moving cumbersome beetle
that cannot fly, so when disturbed it simply tucks its legs under its body and
either drops to the ground or rolls onto its back, keeping perfectly still. In
this state it’s hard to spot in the soil. Eventually, when it thinks the coast
is clear, it stretches out a tentative leg, rocks itself until those
sickle-shaped claws grip a leaf, hauls itself right-way-up and ambles away.
Vine weevils are notorious horticultural pests, because
their larvae feed on the root systems of garden plants - especially those grown
in pots. The first sign of their presence is wilting of the leaves, by which
time they have destroyed most of the root system, symptoms I became aware of
when my collection of show auriculas was devastated by their larvae.
Vine weevils are parthenogenetic, laying fertile eggs without the need for a
male to fertilise them, so it only takes one weevil to start an infestation.
Since they can’t
fly, the vine weevil in our bath must have either climbed in through an open
window, arrived on our clothing or had been carried in on towels dried on the
washing line in the garden.
A random digression
on thanatosis
If, like me, you
were a teenager in the 1960s you might have listened to a rock band called the
Grateful Dead, headed by Jerry Garcia and noted for their eclectic range of
musical genres.
Taxonomists - those
who assign scientific names, rooted in Latin and Greek, to newly-discovered
species, - are not generally noted for whimsy, but in 1987 one fan of the
Grateful Dead, entomologist John H. Epler, honoured them with a scientific name
for a new midge species that performs thanatosis - Dicrotendipes
thanatogratus. The specific epithet, thanatogratus, means ‘grateful dead’,
amalgamating thanatos (Greek for “death”) with gratus (Latin
for “grateful”)
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