Slugs and snails again topped the list of the most troublesome pests, as they have done for eight of the past ten years. Damage from slugs and snails can occur all year round, affecting seedlings and many ornamental plants and vegetables. Plants often affected include potato tubers, hostas and narcissus.
However, a pest that bores into the stems of leeks, onions and garlic leaving plants open to infections made its first appearance on the RHS’s annual list of the top ten garden pests for 2014.
Allium leaf miner was 7th on the list of the most frustrating garden pests. The small white headless maggots of allium leaf mining flies bore into the foliage and stems of their host plants rendering them inedible. The flies are becoming established in new areas throughout Britain and are a serious threat to plants in the onion family (Alliaceae). Gardeners can protect plants from allium leaf miner by growing crops under horticultural fleece.
Rosemary beetle (5th), which feeds on the foliage of aromatic plants including rosemary, lavender, sage and thyme, and tortrix moth (=8th), which feed on fruits and flowers, both indoors and outdoors, made a comeback in 2014.
Mice and voles, about which enquiries hit a 24-year high in 2013, slid down the table in 2014 to joint 8th place. These small rodents pose a number of challenges to gardeners: the tunnelling activities of voles can disturb the roots of plants and disfigure lawns, and they gnaw the bark from the roots and stems of tree and shrubs.
Mice can be a problem in storage areas, and in the garden they take fruit and chew off seedlings. Peaks and troughs in mice and vole populations are thought to be due to changing food supplies and the prevalence of predation and diseases.
Box tree caterpillar is a relative newcomer to the UK with gardeners first reporting the larvae in 2011. Originating in East Asia, box tree caterpillars can grow up to 3cm (1.25in), and can completely defoliate box (Buxus) plants.
Glasshouse thrips have been become an increasing problem and appear to be thriving in sheltered urban gardens, attacking a range of garden plants, particularly Viburnum, causing a silvery discoloration of the upper leaf surface.
RHS Senior Entomologist, Dr Andrew Salisbury says: 'The RHS saw a 42 percent increase in the number of enquiries it received about pests in 2014 compared with the previous year. Due to the great gardening year we have enjoyed, more people were spending more quality time in their gardens and noticing the effects of pests.'
||Glasshouse red spider mite
||Allium leaf miner (fly)
||Tortrix moth caterpillar