Gardening is full of surprises. And right now in my garden they are mainly of the nasty variety. Or rather, one nasty variety. Each time I decant a plant that has overwintered in a pot, out pops a dirty, white herd of Otiorhynchus sulcatus. Vine weevil . . . and the only nice thing that I can discover about this pest is that its Latin name translates as "the handled-snouted furrowed one".
The crescent-shaped, baininwool-coloured larvae have been nestling secretively in the damp, dark compost since they hatched last autumn. During really cold weather they snooze quietly, but the rest of the time they mash away at the roots of plants with their pale-brown nubby heads and ruinous mouthparts. A plant that is in the pink of health one day starts to look a bit peaky and wilted the next, until a few days later - unrevived by watering or feeding - it keels over, severed from its roots. Grubs around now are enjoying their last larval meal before entering the waxy pupal stage - where they wait, eerily, like white-chocolate-coated insects, slowly metamorphosing into adult weevils. Emerging after some weeks, the flightless grown-up is a baroque-looking individual - an entirely different beast from the gelatinous larva - all nose, legs and crooked antennae radiating out of a dull black, ribbed frame. It moves slowly and deliberately, a clockwork toy with a wound-down, lax spring; it even plays dead when disturbed. Actually, "it" is a "she". Always. In the world of the vine weevil there are no males. It's an all-female community of handle-snouted virgins that has evolved so that each one can lay eggs and perpetuate the species without ever having even a sniff of a bloke weevil. It is a fanatic feminist's dream come true - or a misogynist's nightmare. Whichever - I find it creepy. The adults feed on the leaves of various plants, creating notches along the margins. When you see the mark of the "ticket-puncher " you know that the vine weevil is an uninvited guest on your property. After several weeks of playing bus conductor with your best rhododendrons, the broody weevils begin to lay their eggs. Produced in numerous small clutches of two to six, they number hundreds by the time their mother has come to the end of her sole laying season. Less than a millimetre in size, the eggs start off white, and after 12 to 24 hours they go brown. They are all but invisible to our eyes, and no, they are not those peculiar spheres that you find in potted plants from the garden centre - those are fertiliser bombs.
But in fact, according to Dr Paddy Brennan of UCD's Environmental Resource Management department, Otiorhynchus sulcatus is "in every garden centre in Ireland, whether they admit it or not". And many nurseries now, he says, routinely incorporate the pesticide Suscon Green (which is unavailable to the domestic gardener) into their potting compost specifically to control vine weevil. The population explosion of this subtropical species in the temperate world is partially attributable to the widespread use of peat-based compost. Damp peat provides ideal, moist conditions for egg survival: after a wet year there are greater numbers of grubs and adults about, while a dry August and September, says the UCD lecturer, causes dessication of eggs and kills young larvae.
The adults feed at night, and Dr Brennan "used to go out an hour after sundown, turn on my car lights and collect them with a golf umbrella". Subsequent research showed that while vine weevils are keen on many different plants (commercial strawberry and blackcurrant crops have been devastated by them), their favourite amongst rhododendrons is the hybrid `Elizabeth'.
Vine weevils are resistant to almost all chemicals the gardener can buy off the shelf, although Armillatox (the honey fungus control) kills eggs if applied during certain seasons. A new compost containing a vine weevil poison is available in the UK, but this has yet to be approved by our Department of Agriculture, and it is not for use with food crops - which means that it must be pretty potent.
For the moment, the gardener's allies against these pestilential insect-Amazons are various species of naturally-occurring ground beetles, as well as microscopic parasitic nematodes, available during the summer from some garden centres as a "biological control". Currently the commercially obtainable nematodes only work at soil temperatures above 14 Celsius, but researchers in Britain have identified a new nematode that thrives at much lower temperatures. In the meantime, any grubs you find will be snapped up by visitors to the bird table, or residents of the garden pond.