If your rhubarb leaves look like Swiss cheese, you’re likely hosting a colony of rhubarb curculio weevils or hungry slugs. Figuring out what is eating my rhubarb leaves is the first step to saving your harvest, and the answer is usually visible if you know where to look.
Rhubarb is a tough plant, but it has a few persistent enemies. The damage you see—holes, notches, or skeletonized foliage—tells you exactly which pest is responsible. Let’s identify the culprit by the evidence they leave behind.
What Is Eating My Rhubarb Leaves
The most common offenders are slugs, rhubarb curculio weevils, and snails. Each leaves a distinct pattern of destruction. You might also see aphids, leaf miners, or even hungry deer, but the first three are the usual suspects for serious leaf damage.
Start by inspecting your plants at night with a flashlight. Slugs and snails are nocturnal and will be actively feeding after dark. If you see shiny, slimy trails on the soil or leaves, you have a mollusk problem.
If you notice small, round holes with a yellowish halo, that points to the rhubarb curculio. This weevil is a snout beetle that chews distinctive holes and lays eggs inside the leaf stalks. The damage is cosmetic for the leaves but can weaken the plant over time.
Slugs And Snails
Slugs are the number one rhubarb leaf eater in most gardens. They rasp away the leaf tissue, leaving irregular, ragged holes. They prefer the tender, young leaves near the ground.
- Look for slime trails on the soil surface
- Check for damage after rain or heavy dew
- Inspect the underside of lower leaves for hiding slugs
Slugs thrive in cool, damp conditions. They hide under mulch, boards, or leaf litter during the day. If you have a thick layer of mulch around your rhubarb, you are providing them with a perfect home.
To confirm slugs, go out at night with a flashlight. You will see them actively feeding. They range in size from tiny gray specks to large brown or black worms several inches long.
Rhubarb Curculio Weevil
The rhubarb curculio is a less common but very specific pest. This weevil is about half an inch long, covered in yellowish-brown powder, and has a distinctive snout. It chews small, round holes in the leaves and stems.
The female weevil lays eggs in the leaf stalks, which can cause the stalk to ooze or become distorted. The larvae then tunnel down into the crown of the plant, which can be fatal over several years.
Unlike slugs, curculio damage appears as clean, punched-out holes. You wont see slime trails. You might see the weevils themselves sitting on the leaves during the day, especially in early summer.
Aphids And Leaf Miners
Aphids are tiny, soft-bodied insects that cluster on the undersides of leaves. They suck sap, causing the leaves to curl, yellow, and become sticky with honeydew. They rarely cause holes, but heavy infestations can stunt growth.
Leaf miners are the larvae of small flies. They tunnel between the leaf layers, creating winding, white or brown trails. This damage is mostly cosmetic and rarely kills a mature rhubarb plant.
If you see distorted new growth with clusters of tiny green or black bugs, you have aphids. If you see squiggly lines on the leaf surface, you have leaf miners. Neither of these are as destructive as slugs or curculio.
How To Identify The Damage Pattern
Look at the specific type of damage on your leaves. This is the fastest way to diagnose the problem without waiting for nightfall.
Irregular Holes And Ragged Edges
This is classic slug or snail damage. The holes are not uniform and often have a chewed, tattered look. You will find this damage on lower leaves first, close to the soil.
Slugs also leave behind a dried, silvery film on the leaf surface. This is a surefire sign that they have been active. The damage worsens during wet weather.
Small Round Holes With Yellow Halos
This is the signature of the rhubarb curculio. The holes are clean and circular, about the size of a pencil eraser. The surrounding tissue turns yellow or brown.
You may also see small, dark specks of frass (insect droppings) near the holes. The weevils are most active in June and July, which is also when they lay eggs.
Scorched Or Skeletonized Leaves
If the leaf tissue is gone but the veins remain, you are looking at a severe slug infestation. They eat the soft tissue and leave the tougher veins behind. This is called skeletonizing.
This type of damage can also be caused by sawfly larvae, which are small caterpillar-like insects. They feed in groups and can strip a leaf quickly. Check the underside of the leaf for these green or black larvae.
Effective Control Methods
Once you know what is eating my rhubarb leaves, you can choose the right control method. Start with the least toxic options first, especially since you are growing a food crop.
Handpicking And Trapping
For slugs and weevils, handpicking is very effective. Go out at night with a flashlight and a bucket of soapy water. Drop any pests you find into the bucket.
- Check the leaves and stems thoroughly
- Look under the crown and around the base of the plant
- Repeat nightly for a week to break the breeding cycle
You can also set up traps. A shallow dish of beer sunk into the soil will attract and drown slugs. Place a board or piece of wet cardboard on the ground near the rhubarb. Slugs will hide under it during the day, and you can scrape them off and dispose of them.
Physical Barriers
Copper tape is a great deterrent for slugs. When they cross it, they receive a mild electric shock. Wrap copper tape around the base of a raised bed or around the rhubarb crown itself.
Diatomaceous earth is another option. This sharp powder cuts the slugs’ bodies, causing them to dehydrate. Sprinkle it around the plant, but reapply after rain.
For curculio weevils, you can use a drop cloth. Spread a cloth under the plant and shake the stems. The weevils will fall onto the cloth, and you can collect and destroy them.
Organic Sprays And Dusts
Neem oil is effective against aphids and some beetles. It works by disrupting the insect’s hormones. Spray the undersides of the leaves thoroughly, as this is where most pests hide.
Insecticidal soap is another safe option for aphids. It suffocates the soft-bodied insects on contact. You can make your own with a teaspoon of mild dish soap in a quart of water.
For slugs, you can use iron phosphate bait. This is safe for pets and wildlife, and it kills slugs within a few days. It is much safer than metaldehyde-based baits, which are toxic to dogs.
Preventing Future Infestations
Prevention is always better than cure. A healthy rhubarb plant can tolerate a few pests, but a stressed plant will suffer more damage. Keep your plants vigorous and clean.
Clean Up Debris
Remove dead leaves, old mulch, and weeds from around the rhubarb. These provide hiding spots for slugs and weevils. Keep the area around the crown clear and tidy.
In the fall, cut back the dead foliage and dispose of it. Do not compost it, as the eggs or larvae may survive the winter. This removes the overwintering sites for many pests.
Watering Practices
Water your rhubarb in the morning so the leaves dry out during the day. Wet leaves are more susceptible to fungal diseases and attract slugs. Use drip irrigation or a soaker hose to keep the foliage dry.
Avoid overwatering. Rhubarb likes moist but well-drained soil. Soggy conditions are a magnet for slugs and can also cause crown rot, which weakens the plant and makes it more vulnerable to pests.
Companion Planting
Planting certain herbs and flowers near your rhubarb can help deter pests. Garlic, chives, and onions are said to repel aphids and weevils. Marigolds attract beneficial insects that prey on aphids.
Nasturtiums are a trap crop. They attract aphids away from your rhubarb. The aphids will prefer the nasturtiums, and you can then remove and dispose of the infested plants.
When To Use Chemical Controls
Chemical pesticides should be a last resort. They can harm beneficial insects and contaminate the soil. If you have a severe infestation that organic methods cannot control, use a targeted product.
For slugs, use a bait containing iron phosphate. It is safe for use around vegetables and breaks down into fertilizer. Avoid baits with metaldehyde, as they are highly toxic to pets.
For curculio weevils, you can use a pyrethrin-based spray. This is derived from chrysanthemum flowers and is relatively safe. Apply it in the evening when the weevils are active.
Always read the label and follow the instructions. Wait the required time between application and harvest. Most products have a waiting period of 7 to 14 days.
Impact On The Harvest
Pest damage on the leaves does not necessarily ruin the stalks. The stalks are the part you eat, and they are often unaffected. However, severe leaf loss can weaken the plant and reduce future yields.
If the damage is mostly cosmetic, you can simply remove the worst-affected leaves. This will clean up the plant and remove any pests that are still feeding. Discard the damaged leaves in the trash, not the compost.
Do not harvest stalks from a plant that is heavily infested. The plant needs its leaves to photosynthesize and store energy for next year. Give it time to recover before you take any more stalks.
Seasonal Timing
Pest pressure varies by season. In early spring, slugs are the main problem. They emerge from hibernation and feed on the new growth. In early summer, the curculio weevils become active.
By late summer, aphids and leaf miners are more common. The plant is also under stress from heat and drought, making it more susceptible. Monitor your plants regularly throughout the growing season.
In the fall, clean up the garden thoroughly. This is the most important step for preventing next year’s infestation. Remove all dead plant material and dispose of it properly.
Frequently Asked Questions
Why are there holes in my rhubarb leaves but no bugs?
Slugs and snails feed at night and hide during the day. You likely have them but are not seeing them. Check the soil surface and under nearby debris for slime trails. Curculio weevils also drop off the plant when disturbed.
Can I eat rhubarb stalks if the leaves have holes?
Yes, the stalks are safe to eat as long as they are not damaged or rotting. The holes in the leaves do not affect the stalks. Wash the stalks thoroughly before cooking. Discard any stalks that have visible weevil damage or oozing.
Will rhubarb leaves grow back after being eaten?
Yes, rhubarb is a perennial and will produce new leaves. However, do not harvest all the leaves at once. The plant needs leaves to gather energy. If all leaves are eaten, the plant may go dormant and regrow next year.
Are rhubarb curculio weevils harmful to humans?
No, they are not harmful to humans. They only feed on rhubarb and a few related plants. The damage is primarily cosmetic. The main concern is that they can weaken the plant over several years if left unchecked.
What is the best natural way to get rid of slugs on rhubarb?
Handpicking at night is the most effective method. Set up beer traps or copper tape barriers as a secondary measure. Diatomaceous earth also works well. Keep the area dry and free of debris to reduce their habitat.
Final Thoughts On Protecting Your Rhubarb
Identifying the pest is half the battle. Once you know what is eating my rhubarb leaves, you can take targeted action. Start with the simplest methods like handpicking and cleaning up debris.
Do not panic if you see some damage. A few holes in the leaves will not kill your plant. Rhubarb is resilient and can recover from moderate pest pressure. Focus on keeping the plant healthy and vigorous.
Check your plants every few days, especially after rain. Early detection makes control much easier. A few minutes of inspection can save you a lot of trouble later in the season.
Remember that a balanced garden ecosystem is your best defense. Encourage birds, toads, and ground beetles, which all eat slugs and other pests. Avoid broad-spectrum pesticides that kill these beneficial predators.
With a little attention and some simple controls, you can enjoy a healthy rhubarb crop all season long. The leaves may show a few battle scars, but the stalks will be perfect for pies, jams, and sauces.
Stay vigilant, and your rhubarb will reward you with a bountiful harvest. The pests are persistent, but so are you. Now you have the knowledge and the tools to win the fight.
One last tip: if you see large, ragged chunks missing from the leaves, it might be deer or rabbits. They will eat the entire leaf, not just chew holes. In that case, a fence is your best option.
Take a deep breath and inspect your garden tonight. You will likely find the culprit quickly. Once you do, you can implement the right solution and move on with your day.