Clover Weevils
Sitona hispidulus and related species
Small weevils of clover and other legumes whose adults notch the leaf edges while the more damaging grubs feed below ground on the roots. The clover root curculio is the main one: its root feeding saps plant vigor and opens the door to root rots and wilt in clover and alfalfa.
🔎 How to spot it
The adult clover root curculio is a tiny weevil only about a sixth of an inch (4 mm) long, with brown wing covers marked with black, white, and gray stripes and spots and clothed in short stiff hairs. The grub is a small white, legless larva with a light brown head that feeds in the soil on the roots. Above ground, the giveaway is small semicircular notches chewed from the edges of the leaves by the adults.
🥀 Damage it causes
Adult feeding leaves crescent-shaped notches along the leaf margins, which is usually minor. The serious damage is done by the grubs, which tunnel through and feed on the taproot and root nodules, scarring and sometimes girdling the roots; this cuts the plant ability to take up water and nutrients, reduces vigor, and creates wounds that let in root-rot and wilt pathogens.
🛡️ Prevent it
Because no insecticides are reliably effective against the soil-dwelling grubs, management is cultural: rotate clover and alfalfa with non-legume crops such as cereals to break the cycle, and keep stands vigorous so plants can outgrow the root injury. Plowing under old, heavily infested stands before replanting helps lower carryover.
🧯 If it is already here
There is no dependable rescue spray once the grubs are feeding in the roots, so control rests on rotation, vigorous stands, and avoiding replanting legumes straight back into an infested field. Good fertility and moisture help damaged plants compensate for the lost roots.
💡 Good to know
The weevil can overwinter as adults or as eggs; overwintered adults lay eggs at the soil surface near the plant base, and the grubs feed on the roots before pupating in the soil. Besides the clover root curculio, the lesser clover leaf weevil attacks clover, its larvae feeding in the shoots, buds, and flowers and cutting seed yields in red clover. Both are weevils of clover and related legumes.
🌱 Plants it attacks
2 plants in the library can be attacked by this pest
For educational and informational purposes only. Pest control advice is general guidance drawn from university cooperative extension sources; always identify a pest positively and read and follow the label on any product before use, especially around food crops, children, and pets.