Vine weevil 'playing possum'

 

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”)