If you’re finding holes, notches, or missing chunks in your beautiful dahlia foliage, you’re likely wondering what’s eating my dahlia leaves. It’s a frustrating sight for any gardener who has nurtured these plants from tuber to bloom. The good news is that by learning to identify the culprits, you can take effective action to protect your plants.
This guide will help you become a detective in your own garden. We’ll look at the most common pests, the specific damage they cause, and the best methods for dealing with them. With a little knowledge, you can reclaim your dahlias and enjoy their stunning display all season long.
What’s Eating My Dahlia Leaves
Several insects and creatures find dahlia leaves as attractive as we do. The type of damage is your first clue. Here’s a breakdown of the usual suspects.
Chewing Pests: The Leaf Munchers
These pests physically eat the leaf tissue, leaving behind very visable damage.
- Caterpillars: Including armyworms, cutworms, and cabbage loopers. They create large, irregular holes in leaves and sometimes sever young stems.
- Slugs and Snails: These nighttime feeders leave behind large, ragged holes and a tell-tale silvery slime trail on leaves and soil.
- Earwigs: They chew irregular holes and can skeletonize leaves, often hiding in the blooms or under debris during the day.
- Japanese Beetles: These metallic pests skeletonize leaves, eating the tissue between the veins so only a lace-like framework remains.
- Grasshoppers and Crickets: They cause large, chomped-out sections, often starting from the leaf edges.
Sucking Pests: The Sap Stealers
These pests pierce the plant and suck out the juices, causing different symptoms.
- Aphids: Tiny, pear-shaped insects (green, black, or red) that cluster on new growth and undersides of leaves. They cause curling, stunting, and leave a sticky “honeydew” residue.
- Spider Mites: Extremely tiny pests that create fine webbing on the undersides of leaves. Leaves develop a stippled, yellow look and may drop off.
- Thrips: Slender, tiny insects that scrape at leaves and petals, causing silvery streaks, white spots, and distorted growth.
- Leafhoppers: Small, wedge-shaped insects that hop when disturbed. Their feeding causes a stippled or whitened appearance on leaves.
Other Potential Culprits
Sometimes, the damage isn’t from insects at all.
- Deer and Rabbits: These mammals can cause significant, clean-cut damage, often eating entire leaves or stems. Deer can reach higher up, while rabbits feed closer to the ground.
- Foliar Nematodes: Microscopic worms that live inside the leaf, causing angular, yellow-to-brown wedges between the leaf veins.
How to Identify the Pest: A Step-by-Step Guide
Follow these steps to pinpoint the problem.
- Examine the Damage: Look closely at the leaves. Are they chewed, skeletonized, or discolored? Note the pattern.
- Check the Time: Inspect plants at different times. Slugs feed at night; many caterpillars feed in the evening or morning.
- Look Under Leaves: Turn leaves over. Most sucking pests like aphids and spider mites reside on the underside.
- Search the Soil: Look near the base of the plant for cutworms, slugs, or their hiding spots.
- Use a Flashlight at Night: This is the best way to catch nocturnal feeders like slugs, earwigs, and some caterpillars in the act.
Effective Control Methods for Each Pest
Once you’ve identified the pest, you can choose a targeted response. Always start with the least toxic option.
For Chewing Insects (Caterpillars, Beetles)
- Hand Picking: For larger pests like Japanese beetles and caterpillars, drop them into a bucket of soapy water. It’s immediatly effective.
- Bacillus thuringiensis (Bt): This natural, soil-borne bacteria is excellent for caterpillars. They ingest it and stop feeding within days.
- Neem Oil or Insecticidal Soap: These organic options work on contact against soft-bodied pests and can deter feeding.
- Row Covers: Use lightweight fabric covers to physically block pests from reaching young plants.
For Slugs and Snails
- Beer Traps: Sink a shallow container filled with beer into the soil. Slugs are attracted, fall in, and drown.
- Diatomaceous Earth: Sprinkle a ring of this powder around plants. It’s sharp on a microscopic level and deters soft-bodied pests (reapply after rain).
- Copper Tape: Applying tape around pots or raised beds gives slugs a slight electric shock, repelling them.
- Hand Picking at Night: With a flashlight and gloves, this can significantly reduce populations.
For Sucking Insects (Aphids, Mites)
- Strong Water Spray: A blast from your hose can dislodge aphids and spider mites. Repeat every few days.
- Insecticidal Soap: Very effective against soft-bodied sucking pests. It must contact the pest directly.
- Horticultural Oil: Smothers eggs and overwintering pests. Use according to label directions, usually in dormant season or early growth.
- Beneficial Insects: Introduce or encourage ladybugs, lacewings, and predatory mites, which are natural predators of these pests.
For Deer and Rabbits
- Physical Barriers: Fencing is the most reliable method. For rabbits, a 2-foot tall fence buried slightly. For deer, a fence at least 8 feet tall is often needed.
- Repellents: Commercial or homemade sprays (like egg or garlic mixtures) can deter mammals, but they need frequent reapplication, especially after rain.
Prevention is the Best Medicine
Keeping your dahlias healthy from the start is key to preventing major infestations.
- Choose Resistant Varieties: Some dahlia cultivars show more resistance to pest damage. Research before you buy.
- Practice Clean Gardening: Remove plant debris in fall to eliminate overwintering sites for pests and disease.
- Encourage Biodiversity: Plant a variety of flowers and herbs to attract beneficial insects that prey on pests.
- Inspect Regularly: Make a habit of checking your dahlias every time you water. Early detection makes control much easier.
- Avoid Excess Nitrogen: Too much nitrogen fertilizer promotes soft, sappy growth that is very attractive to aphids.
- Water at the Base: Overhead watering can create humid conditions that favor some pests and foliar diseases.
When to Consider Stronger Measures
If an infestation becomes severe and non-chemical methods aren’t enough, you might consider a targeted pesticide. Always read the entire label carefully. Choose products specific to the pest and safe for use on dahlias. Apply in the evening to minimize harm to pollinating insects like bees. Remember, even organic pesticides can harm beneficial bugs, so use them judiciously.
FAQ: Common Questions About Dahlia Pests
What is making tiny holes in my dahlia leaves?
Tiny holes are often caused by flea beetles or the early feeding of other small beetles. They create a “shot-hole” appearance. Check for tiny, jumping insects on the leaves.
Why are my dahlia leaves curling up?
Leaf curling is a classic sign of aphid infestation. Check the undersides of leaves and the tender new growth for clusters of small, soft-bodied insects.
What can I put on my dahlias to stop bugs from eating them?
Start with physical removal and barriers. Then, consider a natural spray like neem oil or insecticidal soap as a deterrent and treatment. Consistency is important for these options.
Are earwigs bad for dahlias?
Earwigs can be both pests and beneficals. They do eat dahlia petals and leaves, but they also consume aphids and other small pests. Control them if their damage is excessive, using rolled newspaper traps or diatomaceous earth.
How do I get rid of slugs on my dahlias naturally?
The most effective natural methods are nightly hand-picking, setting beer traps, and creating barriers with diatomaceous earth or copper tape around your plants.
Figuring out what’s eating your dahlia leaves is the first and most important step. With careful observation, you can match the damage to the pest and choose a smart, effective response. A combination of prevention, early detection, and targeted control will help ensure your dahlias remain the stunning focal point of your garden, with their leaves as healthy and vibrant as their famous blooms. Remember, a few holes might be inevitable, but with these strategies, you can keep your plants thriving.