Skip to Content

Budworms Eating Your Petunias? Fight Back With These 5 Surefire Methods

Budworms Eating Your Petunias? Fight Back With These 5 Surefire Methods

Share this post:

Disclaimer: Some links found on this page might be affiliate links. If you click an affiliate link and make a purchase, I might earn a commission. As an Amazon Associate I earn from qualifying purchases.

Petunias and geraniums are gorgeous colorful flowering plants to have in your garden. Until the moths start hovering around!

Before long, you’ll need to go to battle with their eggs and larvae that’ll devour the foliage and potentially stop your petunias from blooming. In that respect, knowing how to get rid of budworms is part of petunia care. They’re fast becoming a common pest!

The budworms that destroy your plants are the larvae of the moth. To get rid of them, you need a plan… a battle plan to get rid of budworms on petunias, and geraniums, and they can also take up residence in roses and snapdragons, too!

Whenever you start to see the presence of budworms, it’s time to equip yourself with the knowledge you need to apply the right treatment that’s effective at ridding budworms without (necessarily) affecting pollinating insects with insecticides, or pesticides.

5 Methods for Getting Rid of Budworms on Petunias

1 – The Laborious Method of Hand-Picking Them

The first choice is by far the safest and that’s because you’re not applying anything to the plant that could risk the health of pollinating insects and your tender petunia plants.

As soon as you start applying non-specific chemical treatments to target species, you can wind up killing off beneficial insects like honeybees, and hummingbirds.

The manual method is repetitive and tedious though and needs to be done nightly. Budworms are nocturnal feeders.

During the day, they’ll be hiding near the soil line. In the evening, there are fewer birds around that would devour them. They come out of hiding when the sun goes down. That’s when to go at your petunias, hand-picking the budworms off.

They’re not always easy to spot because they camouflage well. Most are green, are under an inch in size, and crawl around on the green foliage of petunias.

Take a flashlight and inspect each leaf, top and bottom side. Once you find them, pick them off and deal with them however your conscience allows. Some people will squish them, others will toss them in a bucket of soapy water.

2 – Treat with Insecticides Containing Bacillus Thuringiensis Kurstaki (Btk)

Bacillus thuringiensis kurstaki (Btk) is among the most effective selective caterpillar killers on the market. This is one of the most highly recommended methods for dealing with budworms on petunias. Not so much for budworms on geraniums.

That’s because of how the budworms feed. On geraniums, they bury themselves deep into the flower buds. On petunias, the buds aren’t as deep, causing the budworms to feed more on the foliage and the flowers rather than feeding from within the bud where chemical sprays and dust powders won’t reach them.

Since the budworms feed more on the foliage and flowers on petunias, Btk can be an effective mitigator to get rid of them, provided the applications are repeated. You’ll never be able to eradicate an infestation with a single treatment because it’s ineffective on the eggs. It only effects the larvae.

When using Btk, remember that it has an extremely short life once it’s exposed to air. The effects are fast-acting (although not instant), provided the caterpillars consume it. They don’t die right away, but as it acts as a stomach poison, they will stop eating holes in the leaves on petunias.

You can get it in spray form, or powder. Apply liberally following the manufacturer’s instructions on the product label. For best results, coat the plant’s leaves in the evening when budworms are actively feeding. Before long, you’ll notice a significant reduction in budworm damage.

Once treated, monitor plants for any re-emergences and start treating with Btk again as soon as you see any budworms on your plant, or any signs that something has been eating your petunias.

Brand names of insecticides that contain Btk…

  • Ferti Lome Caterpillar Killer Spray with Bt and Natural Guard Caterpillar Killer Spray
  • Dipel Dust biological insecticide
  • Monterey B.t.
  • Safer® Brand Caterpillar Killer
  • Dipel DF (Dry Flowable). Dipel have four formulations – Wettable powder (Dipel WP), Emulsifiable Suspension (Dipel ES), Dry Flowable (Dipel DF), and Dipel 10G Granule. Dipel DF is the most common treatment for budworms.

Know this too: Numerous insecticides contain a strain of Bacillus thuringiensis, but not all will work on budworms. It needs to be the kurstaki strain to be effective at killing the tobacco budworm.

The Btk strain targets moths and butterflies. Only in the larvae stage though. It won’t have any effect on unhatched eggs so repeated treatments will be required.

For budworm infestations that have progressed to the more advanced stages, Dipel ES is the stronger solution and it can be tank-mixed with an ovicide to make it more effective at killing the eggs. In the U.S. Dipel is a non-restricted use pesticide.

In other countries, licenses may be required for purchase and application, meaning, you may need to hire a certified pesticide applicator to treat your plants with commercial-grade Dipel.

3 – Feed Them Products Containing Spinosad

Spinosad is an organic method for budworm control. It’s made from a soil bacterium by mixing spinosyn A and spinosyn D. The problem with it is that it breaks down fast when exposed to sunlight.

For that reason, it’s best to apply this in the evenings. Once applied, it’s effective for up to three hours. The hotter the temperature is, the faster its degradation.

The effects on beneficial insects are minimal, however, it is advised to wait until most pollinating insects are not around before applying Spinosad to minimize the risk to pollinators. Its efficacy lasts for up to three hours so aim to apply insecticides containing this at dusk when beneficial insects are gone so that only the budworms are actively feeding.

Bonide Captain Jack’s Deadbug Brew contains 0.5% Spinosad as the active ingredient. Enough to poison budworms without impacting beneficial wildlife and insects around your garden.

4 – Spray Your Petunias with Bifenthrin

If you have a greenhouse, or sheltered area where you can move potted petunias away from pollinators, you could treat it with Bifenthrin (a pyrethroid). This is highly toxic to every insect to come into contact with it. So much so that it’s banned in Europe for agricultural use and in some States, it’s only available to licensed applicators.

Consumer-grade insecticides contain extremely low levels of Bifenthrin. Usually, up to 0.3%. professional-grade products such as Bifen I/T contains 7.9% and Bifen XTS contain up to 25.1% – lethal levels that are most commonly used by professional pest control firms to treat and prevent termite infestations.

The only time you’d likely find this level appropriate for use on plants is when infestations are extremely high. Plants can’t absorb Bifenthrin so you can spray them, but, remember, all products containing this are harmful to every insect.

5 – Go the organic Route with Beneficial Nematodes

Two beneficial nematodes that feed on the larvae of moths and butterflies are green lacewing larvae and lady beetles. Particularly, the green lacewing larvae as that is a ferocious feeder of all soft-bodied insects.

Many of the petunia pests like aphids, white flies, thrips, and spider mites (including their eggs) can be brought under control with beneficial nematodes watered into the soil.

To protect against future infestations, plant companion plants nearby that’ll attract predatory wildlife that eat budworms, such as spiders, damsel bugs, and parasitic wasps.

For petunias in the yard, set up a bird feeder nearby to attract birds. Planting herbs like coriander and parsley are good for providing a nesting area for beneficial bugs that’ll help you keep your plants pest-free.

Share this post: