Beware the plant-eating black vine weevil

This is a glorious time in the garden. All the plants have such fresh, lush and perfect foliage.

But lurking in plant debris or under those perfect leaves are foliage predators, waiting for the veil of darkness, when the onslaught will begin.

The culprit is the notorious black vine weevil.

By day they are sluggish and clinging and appear exceedingly innocent. But by night these beasts move quickly up plant stems and gnaw notches along the edges of that lush, perfect foliage.

By August, peonies, rhododendrons, mountain laurel, bergenia, euonymus and lilac, their favorite delicacies, look as though they’ve been at war. If the visual damage isn’t enough, these little pests do their most severe damage below the surface of the soil, as larvae.

Black vine weevils are a half-inch long, black and oval shaped, with a short, broad snout. Their wing covers are well rounded, ribbed and covered with fine yellow hairs.

Weevils cannot fly, as their wing covers are fused. They disperse by walking.

The C-shaped larvae are brown-headed, legless, wrinkled and white.

The black vine weevil has a four-stage life cycle: egg, larva, pupa and adult. Only about 1 percent winter as adults.

In May, after a short feeding period, the larvae develop into pupae. They emerge from the soil as adults in mid-June, feed on foliage a couple of weeks, then lay several hundred eggs at the base of a chosen plant.

Egg laying takes place over a four- to six-week period. There are no males in this species, so all female adults reproduce parthenogenetically.

In 14 days, the eggs hatch, and the small larvae dig into the soil and the root. Then the feasting frenzy begins.

Chemicals can be effective, but a more organic approach is to use parasitic entomopathogenic nematodes. Early June is the best time to introduce themto the soil.

The soil has warmed to 55 degrees, and weevil larvae are present and have not yet emerged as adults. After nematodes have been applied, the soil needs to be kept moist.

Nematodes can be purchased at garden centers or through garden supply catalogs.

Other ways to control this pest are:

“Clear away fallen debris.

“Hand pick or shake onto a white sheet and destroy.

“Place cardboard strips, commercially covered with a sticky compound, around the base of plants.

“Attract house wrens by setting up small birdhouses. They consume multitudes of black vine weevils.