Controlling Beetles and Weevils in the garden

Introduction

There are some weevles which cause damage in the horticulture and the amenities. An important pest species in the ornamentals is the vine weevil, Otiorhynchus sulcatus, while the rose beetle, Phylloperta horticola, causes a lot of damage in the grassland.

Biology

Weevils go through four life stages, namely egg, larva, pupa and adult. Larvae has biting mandibles and mostly feed themselves with the same food as the adults. Some larvae are legless and look like caterpillars.

Damage symptoms

Larvae cause most damage. Smaller larvae feed mainly on root hairs, but the larger larvae feed on roots and the stem base. That hinders growth and eventually causes the plant to turn yellow and wither. One larva is enough to kill a plant, if it girdles the base of the plant stem.

Larvae of the rose beetle Phylloperta horticola cause severe damage to lawns by eating the roothairs of the grass. This reduces the uptake of water and nutrients. Moreover, animals like birds, fox, swine and hedgehogs searching for grubs, damage the lawn seriously.

Degree Day Model for Japanese Beetles:  http://uspest.org/cgi-bin/ddmodel.us?sta=KSLE