Pea and Bean Weevils is a minor pest that affects peas and broad beans.
What does it look like?
Adults are greyish brown, 4 to 5mm long, and tend to fall to the ground when disturbed, so they are hard to spot. The larvae are creamy white, legless grubs with pale brown heads that feed on the nitrogen-fixing nodules on the roots, usually without harming growth in gardens.
What causes it
Growth stage decides whether the feeding matters: there may be a check in growth if small seedlings are heavily fed on, while an established plant tolerates the damage. A seedling that grows quickly through the vulnerable stages outgrows the risk.
Is this pest active now?
Adults are active and feeding from April to July, with one generation a year rather than several waves to track.
🌱 Plants at risk
Symptoms
A series of U-shaped notches around the edges of leaves is the sign to look for. The actual leaf area lost is generally small on an established plant despite how extensive the nibbling can look; a small seedling is the exception, since the same amount of feeding costs it proportionally more.
Life cycle
Adults overwinterKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → hidden away in leaf litter and lay eggs in the surface layers of the soil in late spring. The larvae feed on the root nodules, and the next generation of adults emerges in late summer. There is only one generation a year.
Why this matters in Scotland
A cooler Scottish spring works against the exact thing that protects a seedling from this pest: growing quickly through the vulnerable stage.
A slow start in a cool spring means more weeks at the size where feeding can check growth. Watering and a sheltered start under fleeceA lightweight, breathable fabric laid or draped over plants to trap a little warmth and keep off frost, wind and some flying pests. Full definition → or clochesA small, portable clear cover placed over an individual plant or short row to trap warmth and keep off wind, rain and pests. Full definition → both work against that longer window, though no Scottish figures were found.
Controls: what works
Fleece or cloches: cover seedlings during their vulnerable stage
A cover gives seedlings both physical protection and an earlier start, so they're bigger and less exposed by the time it comes off.
Watering: keep seedlings well-watered to grow through it quickly
Healthy, well-watered seedlings grow faster through the stage where feeding can check their growth, so they spend less time exposed to it than a stressed or under-watered seedling would.
Tolerate notching on established plants
Management is usually unnecessary, because plants can generally tolerate damage from these insects, and the leaf area lost is generally small.
Myths about pea and bean weevils
“U-shaped notches chewed around the leaf edges mean the pea or bean plant is losing a serious chunk of its yield.”
The notching looks alarming because it spreads across almost every leaf, but the actual leaf area lost is generally small even on heavily marked foliage, and established plants tolerate the feeding well. The exception is a small seedling, where the same amount of chewing costs proportionally more and can check its growth.
Our read Extent of visible notching is a poor guide to harm once a plant is past the seedling stage. Growth stage, not notch count, is the thing worth checking.
What to do: On an established plant, leave notched foliage alone. On a seedling, check how much of each leaf is affected and keep it watered so it grows through the vulnerable stage quickly.
1 source
- RHSLeaf area lost is generally small and established pea and broad bean plants can tolerate the feeding, with only small seedlings at risk of a growth check.
“If you spot weevil notching on peas or broad beans, you should reach for an insecticide to protect the crop.”
No chemical control is given for this pest in a garden setting; guidance goes straight to fleece, watering and simply tolerating the damage on established plants instead. That reflects a domestic-scale pest that established plants shrug off, so spraying is treating a cosmetic symptom that was never going to cost the crop anything.
What to do: Skip the spray. Cover seedlings with fleece or cloches during their vulnerable stage and keep them watered; leave established plants to carry on regardless of how notched the leaves look.
1 source
- RHSNo chemical control is recommended; management is usually unnecessary since plants can generally tolerate the damage.
“The visible leaf notching is where this pest does its damage, so that is what to watch for.”
Garden and field guidance point at two different culprits. The RHS frames the adult notching as the visible but largely cosmetic damage, with garden-scale plants coping fine either way. AHDB's guidance for commercial pea and field bean growers instead identifies larval feeding on the root nodules underground, invisible from the surface, as the main driver of any real yield loss, with the notching itself serving mainly as an early warning sign that adults and their eggs are present.
Our read The difference is one of scale, not a contradiction. AHDB is describing crop-loss economics on field-scale sowings; RHS is describing what a garden or allotment plant experiences, where that same larval feeding usually doesn't add up to a growth problem. Both can be right for their own context.
What to do: In a garden bed, judge the plant by its growth, not the leaf notching. If seedlings are struggling despite watering, the underground root-nodule feeding is a more likely explanation than the notches themselves.
“Once pea and bean plants are past the seedling stage, this pest can be ignored completely.”
This is one of the few pest claims that holds up cleanly at garden scale. Established pea and broad bean plants tolerate the adult feeding, and the larvae feeding on root nodules underground do not usually affect plant growth in gardens and allotments either. The seedling stage is the one point worth a closer look; past it, there is nothing further to monitor for.
What to do: Watch closely only while plants are small. Once they are established and growing away, there is no need to keep checking leaves for notching.
In Scotland: A slower Scottish spring stretches the seedling stage out over more weeks, so it is worth confirming plants have reached that established, tolerant size before writing this pest off, rather than assuming it from the calendar date alone.
1 source
- RHSEstablished pea and broad bean plants can tolerate the feeding, and larvae feeding on root nodules do not usually affect plant growth in gardens and allotments.
Frequently asked questions
What should I do first if I find pea and bean weevils in my garden?
The first thing to try: Fleece or cloches. Then: Watering.
Will pea and bean weevils kill my plants?
Not on established plants: the notching looks worse than the loss, because the leaf area lost is generally small. Small seedlings can be checked in their growth if they are heavily fed on.
When should I watch for pea and bean weevils?
Adults are active and feeding from April to July, with one generation a year rather than several waves to track.
Should I just leave pea and bean weevils alone?
On established plants, yes: management is usually unnecessary. Cover seedlings with fleece or cloches and keep them watered so they outgrow the damage.
Sources
Show the source
- RHS1: identification, symptoms, the seedling-vulnerability mechanism, life cycle and overwintering, fleece and cloches, watering, tolerance on established plants, absence of a chemical control