Slugs and snails are number one pest in gardens
26 January 2010
Slugs and snails were the number one problem on the 2009 top 10 garden pests list, according to the RHS.
The RHS Entomology team, based at RHS Garden Wisley, have compiled their annual list of garden pests, based on the enquiries by RHS members during the last year.
Top 10 pests in 2009
- 1. Slugs and snails (various species): As in most years, slugs and snails were the number one problem in gardens and on allotments. Most damage occurs during spring to autumn, affecting seedlings, many ornamental plants and vegetables, especially potato tubers and narcissus flowers. More advice on slugs and snails
- 2. Harlequin ladybird (Harmonia axyridis): This foreign ladybird was unknown in Britain until 2004 but has since spread rapidly throughout the country. It is not a plant pest but causes concern because of its reputation for eating native ladybirds and other aphid predators. Its prey of choice, however, is greenfly and other aphids, so it is of some benefit to gardeners. It can feed on a wide range of other insects when aphids are in short supply but it remains to be seen whether harlequin ladybirds will reduce the numbers of native beneficial insects.
- 3. Lily beetle (Lilioceris lilii): Although established in England since the early 1940s, this pest of lilies and fritillaries did not spread out of the south east counties until the 1980s. It now occurs in all English counties with more scattered occurrence in Wales, Scotland and Northern Ireland. Both the larvae and adults eat the leaves and can cause severe defoliation. More advice on lily beetle
- 4. Vine weevil (Otiorhynchus sulcatus): The adult beetles eat notches in the leaf margins of a wide range of herbaceous plants and shrubs. The larvae feed on plant roots, especially those being grown in pots or other containers. It is one of the few pests capable of killing plants and it is a top five enquiry in most years. More advice on vine weevil
- 5. Chafer grubs (various species): Chafer grubs are the larvae of several species of chafer beetles. Most of the damage occurs in lawns where the grubs of garden chafer (Phyllopertha horticola) and Welsh chafer (Hoplia philanthus) eat the roots. During autumn to spring other animals, such as foxes, badgers and crows, rip up the loosened turf to feed on the grubs. More advice on chafer grubs
- 6. Viburnum beetle (Pyrrhalta viburni): The principal host plants are Viburnum opulus, V. lantana and V. tinus but some other Viburnum species may also be attacked. Most of the damage is done by the larvae, which can reduce the foliage to lacework during May-June. The adult beetles also eat the leaves in late summer but less extensive damage occurs at that time.
- 7. Pear leaf blister mite (Eriophyes pyri): This microscopic mite lives inside the foliage of pear trees, causing reddish pink or pale green blisters on the foliage in the spring. By mid-summer the affected parts of the leaves have turned blackish brown, giving heavily infested trees a very unhealthy appearance.
- 8= Ants (mostly Formica and Lasius spp.): Ants tend to be most abundant in sunny gardens with well drained soils. They cause little direct damage to plants but the soil excavated from their nests can be a nuisance in lawns, on patios and in flower beds where low-growing plants may become partly buried. Although there are insecticides for ant control, it is difficult to eliminate nests from gardens and so the presence of ants has to be tolerated. More advice on ants
- 8= Rabbits (Oryctolagus cuniculus): Rabbits eat the foliage of many low-growing ornamental plants and vegetables. They also damage the bark of trees and shrubs, sometimes fatally, especially in hard winter weather when other plants are frosted or snow-covered. More advice on rabbits
- 10. Capsid bugs (Lygocoris pabulinus and other species): Capsid bugs attack a wide range of herbaceous plants and shrubs. They suck sap from the shoot tips and flower buds. This feeding kills some of the cells in the leaves developing inside the buds. As the leaves emerge and expand, the dead cells tear into many small holes, giving the leaves a tattered and distorted appearance. Flowers may also be distorted or, in the case of fuchsia, fail to develop. More advice on capsid bugs
The cool, wet conditions of the 2009 summer were ideal for snails and slugs.
The non-native harlequin ladybird produced the second largest number of enquiries, although it is not a pest in the conventional sense. Since its arrival in 2004, it has caused a nuisance by coming into houses to hibernate in the autumn. It has also been given a bad reputation as a destroyer of native ladybirds and other aphid predators.