Q What is pea and bean weevil?

A It is a common weevil (Sitona lineatus) found on peas and broad beans. The adults, which are seldom seen, are brown beetles with creamy stripes, 5mm and long feed on leaves and the grubs or larvae feed on the roots.

Caption: Pea and bean weevil make characteristic notching round the leaf edges

Q Does pea and bean weevil cause serious damage?
A The adults make characteristic U-shaped notching all round the leaf edges in spring. Although they do spread viral diseases, they do not usually do significant damage in the garden unless very young plants are attacked. Usually, however, the plants will grow out of the vulnerable stage with little loss of crop.

The larvae feed on the roots of the plant and are only noticeable when the crop is pulled up. They are small (up to 5mm long) white grubs with no legs and brown heads, that look very like vine-weevil grubs. They can sometimes be seen feeding on the nitrogen-fixing nodules.

Q When should I expect pea and bean weevil attacks?
A Adult weevils overwinter in vegetation and old plant debris and emerge in spring. If this coincides with the emergence of seedlings, the damage can be severe. Eggs are laid around plants from April until July. The grubs hatch after about three weeks and feed on the plant roots. By late June they pupate about 5cm deep in the soil, and about two weeks later the adults emerge. Because the older beans and peas have tough leaves at this stage of the season, the weevils seldom do much damage. In fact, they feed on clover until the cold weather comes, when they find their overwintering sites.

Q What can I do about pea and bean weevils?
A Prepare the soil well, making a fine tilth. If the soil is poor, boost the seedlings' growth before sowing by adding extra fertiliser, such as growmore (rake in 70g a sq m). Water the young plants if necessary to keep them growing steadily and cover them with garden fleece in cold weather. Covering before the seedlings emerge will exclude not only pea and bean weevil, but also blackfly and birds too. Keeping the rows well hoed will also reduce the chances of damage. There is no realistic physical way of controlling the root-eating larvae. There are no chemical controls available for adults or larvae. An alternative is to start broad beans off in pots to plant out when large enough to avoid serious damage.