Pea and Bean Weevils is a minor pest that affects peas and broad beans in Scotland. Here is what it looks like, how to spot the damage, and which controls have been tested.
What does it look like?
Adults are greyish-brown, 4-5mm long, and drop to the ground the moment they're disturbed, which makes them genuinely hard to actually catch in the act. Larvae are creamy white, legless grubs with pale brown heads, feeding out of sight underground on root nodules rather than on visible growth.
What causes it
Growth stage decides whether this feeding actually matters: a small seedling can genuinely be checked in its growth by heavy feeding, while an established plant shrugs off the same damage with no lasting effect. A seedling growing quickly through that vulnerable window outgrows the risk; one growing slowly stays exposed to it for longer.
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.
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 → in sheltered places, then lay eggs in the soil near host plants in late spring. Larvae feed unseen on the root nodules that fix nitrogen for the plant, through summer, before pupating in the soil, and the next generation of adults emerges in late summer.
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 slower start here means more weeks at the size where feeding can actually check growth, compared with a warmer spring further south. Watering well and an earlier, 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 directly against that longer window.
Controls: what actually works
All the methods below are backed by real evidence, not just repeated folklore.
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
Seeing notched leaves on an established plant isn't a cue to reach for a spray or start treating it: there's no amateur chemical option for this pest anyway, and the plant is already coping fine on its own.
Myths about pea and bean weevils
4 common claims about pea and bean weevils, checked: 2 busted1 disputed0 untested1 hold up
“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 genuinely 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 actually 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 disagreement is really about scale, not a genuine 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 genuinely 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 actually 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?
Start with fleece or cloches. After that, watering. Work through the rest in order of how well-evidenced they are if the first two aren’t enough on their own.
Will pea and bean weevils kill my plants?
They rarely kill established plants. The damage is usually cosmetic on outer leaves, and natural predators often bring numbers under control without you doing anything.
When are pea and bean weevils most active in Scotland?
Check the seasonal activity section above. Scottish timings can run a few weeks behind the UK-generic figures.
Should I just leave pea and bean weevils alone?
In most gardens, yes. pea and bean weevils are food for birds, wasps and predatory insects, and a healthy garden carries some without trouble. Tolerance is also RHS's official position now, for that same reason.
Sources
1 source, recorded with what each was used for
- RHS1: identification, symptoms, the seedling-vulnerability mechanism, life cycle and overwintering, fleece and cloches, watering, tolerance on established plants, absence of a chemical control