There are some beetles which cause damage in the horticulture, arable farming and public green spaces. A common pest species in the ornamentals is the black vine weevil, Otiorhynchus sulcatus, while the garden chafer, Phyllopertha horticola, causes a lot of damage to grasslands. Asparagus growers face the problem of the common asparagus beetle (Crioceris asparagi).Capnodis tenebrionis is one of the most common pests in cultivated stone fruit (such as cherries, apricots and almonds) and in some cases seed fruit (apples and pears). The beetle has been a serious threat in the Mediterranean area and Middle-East for several decades.
Beetles go through four life stages, namely egg, larva, pupa and adult. Larvae have biting mandibles and mostly feed on the same food as adults. Some larvae are legless and look like caterpillars.
- Vine weevils are only active at night. They take semi circular bites along the edges of the leaves. This notching decreases the ornamental value of the plant. Larvae sometimes damage shrubs and young trees by feeding on buds and soft bark.
- Larvae cause most damage. Smaller larvae feed mainly on root hairs, but the larger larvae feed on roots and the stem base. That hampers 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.Click here for more information about combating vine weevils and other weevils using biological methods.
- Larvae of the garden chafer, Phyllopertha 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, can seriously damage the lawn.
- The larvae of the common asparagus beetle eat the parts of the asparagus plant that are above ground. The larvae climb down the plant to pupate in the soil. The adults eat only asparagus foliage. Click here for more information about combating grubs using biological methods.
Adults of Capnodis tenebrionus feed on twigs and young branches mainly causing problems in tree nurseries and young plants. The greatest damage is caused by the larvae. They penetrate the roots of the trees and feed on the cortex. Young trees die as a result of this damage. Just a few larvae are enough to cause the death of an adult tree in 1 or 2 years.