Beautiful green Hosta leaves appear rich and delicious, and a slew of garden pests agree! Without treatment, they will be nibbled on by many insects, leaving their otherwise thick and verdant plantings riddled with holes and raggedy-looking leaves.
Hostas can be sprayed with a commercial garden insecticide as an effective control measure. However, neem or horticultural oils are preferred because they protect pollinators and other beneficial insects regardless of what you spray.
New plantings are especially vulnerable to being chewed to death, and pests can be the final straw that pushes your Hostas over the edge and end during times of stress.
In addition, I spray for specific species. For example, grasshoppers are my minor favorite garden pest because they are resistant to predators and other natural control measures, so I frequently spray to keep them from becoming a plague.
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How to Spray Pests on Hostas
Always read the label instructions before spraying and wear appropriate equipment and protective gear. Gloves are required, and for larger areas, I recommend wearing eye protection as well.
Spray only infected plants and those nearby, not the entire garden. This will ensure that your beneficial bugs survive while the pests die off.
I also recommend spraying early in the day or late in the evening. Many insecticides can cause leaf burns if they are still wet when the sun hits them. In hot weather, it’s also a good idea to water thoroughly before spraying.
Finally, get under the leaves and into the nooks and crannies around stems and stalks. Bugs prefer to hide in small spaces, and eggs are frequently discovered under leaves. You should spray the entire plant to get rid of all the bugs.
Pest Sprays For Hostas
| Pest | Effective Pest Control |
| Earwig | Permethrin Insecticide |
| Boxelder Bugs | Pyrethrin insect spray |
| Red Lily Beetles | Neem oil |
| Scale | Horticultural Oil |
| Mealybugs | Insecticidal soap |
| Grasshoppers | Carbaryl based insecticide |
| Wooly Aphids | Insecticidal soap |
| Aphids | Neem oil |
| Black Vine Weevil | Systemic Insecticide |
| Earwigs | Insecticidal soap |
Earwigs
Hostas are a favorite food of earwigs. They are brown insects about 5/8 inch long with forked pincers on their backs.
They’ll hide in stems or under leaf litter near the Hosta’s base. Damaged leaves have a ragged edge, with uneven rips and tears in the foliage’s borders.
Control
There are a few non-chemical earwig control methods. Earwigs enjoy mulch, so removing excess will help keep them in check. You can also catch them in shallow oil dishes.
If you must spray, a permethrin insecticide is better than most. While it is still a potent poison, it is less dangerous to other animals.
Boxelder bugs
Boxelder bugs (Boisea trivittata) are sizable black beetles with long spindly black legs and flat bodies that feature distinctive red markings.
They’re often found around boxelder, maples, and ash trees but aren’t fussy about what they eat. Instead, they dine on your Hostas’ vital fluids, sucking the life from the poor plant through a sharp but narrow proboscis.
Control
When they appear in small numbers, boxelder can be removed from Hostas with a sharp shake of the afflicted leaf. You can crush them, though be warned – they release a foul smell when crushed.
If you want to use chemical agents, typical insecticides that contain Pyrethrum are ideal.
This lower-impact pesticide is generally nontoxic to cats and dogs when used correctly. In addition, it’s commonly used to treat fleas in pets, making it one of the safer options for the garden.
Red Lily Beetles
Red Lily beetles (Lilioceris lilii) are bright red beetle around 1/4 inch to 3/8 inch (6 to 9.5 mm) long.
Their larvae are more extensive, about 1/2 inch or so, with tan-colored bodies often unpleasantly layered with their droppings.
This disgusting habit camouflages them and makes them unpalatable to birds and other large predators.
Lily beetles lay bright red eggs on the underside of leaves, so you may well spot the eggs before you spot the unfortunately camouflaged larvae.
Control
In most of the continental United States, lily beetles are a vital food for pest-eating wasps who hunt them enthusiastically.
It’s important to avoid harming them when treating lily beetles, so neem oil is your best option. It’ll knock out the beetles while leaving the wasps to fight another day.
Scale
A scale is a group of minor shield shape bugs of many species. They’re usually relatively tiny, no more than a 1/2 inch in size, and can range in color from white to black and any shade between, with most a nondescript brown.
They’re sap suckers and love to cluster on stems and leaf veins, where they feast on the Hosta’s vital fluids.
Control
Scale is resistant to most sprays, thanks to their shield-like outer layer, so you’ll need to use horticultural oil instead.
When applied liberally to the undersides of leaves and stems, it will work its way underneath as younger ‘crawler’ stage scale bugs move around.
You’ll need to re-apply at week-long intervals to ensure you kill off each subsequent generation.
Mealybugs
Fluffy little monstrosities, mealybugs range in size from 1/20 inch to larger 1/5 inch specimens and are often covered in a soft layer of fibers.
They are sap suckers, draining fluid from leaves and leaving them pale, wilted, or yellowing.
Control
Due to their soft outer layer and diet of sap, it’s tricky to poison a mealybug with sprays. Insecticidal soaps are best, as they kill off younger bugs before adulthood.
You’ll need to repeat the spraying every ten days to kill off newly hatched eggs.
Grasshoppers
Grasshoppers are my all-time least favorite garden pests. In warm weather, it’s frighteningly easy to watch them go from one or two-inch-long hoppers to a Biblical plague of giant insects devouring everything in sight.
In addition, they are migratory and can fly considerable distances, making control very difficult.
Control
I will break out the big guns and apply a powerful chemical insecticide for grasshoppers.
However, I recommend a carbaryl-based insecticide like Sevin, as it’s effective for the longest while still being relatively safe. Spray as soon as you see the most minor ‘hopper’ stage.
Woolly Aphids
Commonly mistaken for mealybugs or even for an outbreak of fungal disease, woolly aphids (Eriosoma lanigerum) are white insects that cover themselves in white waxy threads.
Like the mealybugs they mimic, they cluster in large groups at the junctions of leaves and branches to suck the sap from Hosta leaves.
Control
Like mealybugs, the Woolly aphid’s white fluff protects it from most sprays. Insecticidal soap is a good approach, as is neem oil. I also find it very satisfying to pluck them from the leaves by hand.
Aphids
Aphids are a collection of small insects ranging in size from 1/16 inch to 1/8 inch in length. They range in color from white to green, as well as brown or cream.
They’re sap suckers and form thick bands around stems, stalks, and the veins of leaves. While they do very little damage, they can transmit diseases from plant to plant.
Control
The prodigious speed at which aphids breed makes them a huge pain to control with sprays. I’ve had far better success with natural controls, such as releasing ladybugs.
But if you must spray, neem oil is best. It doesn’t kill the aphids outright but instead reduces their appetite.
As a result, they stop eating and starve to death. You’ll need to repeat treatment every five to ten days to ensure all aphids are killed.
Black Vine Weevil
The Black vine weevil (Otiorhynchus sulcatus) is a stubby black bug with a short snout and a small, fat rump.
It’s around 3/8 inch long, with a long antenna. It produces slightly larger, legless, curved grubs with a brown heads.
There’s not a part of the Hosta that this weevil won’t eat. The grubs love the roots, often chewing notches or bands from them. The adults eat leaves and prefer mature growth to new shoots.
Control
Because the black vine weevil eats all parts of the plant, the best bet is a systemic pesticide.
This spray contains insecticides taken up by the Hostas, working their way into the plant’s tissue. As the weevil eats the tissue, it’s poisoned by the plant it dines upon.
How Do I Keep Bugs from Eating My Hostas?
Commercially available sprays are one of many options for controlling pests. There are plenty of other options available that will get the job done just as well.
1- Pyrethrin Sprays
Derived from a naturally occurring substance found in chrysanthemums, Pyrethrin spray is often touted as an alternative to harsh chemicals.
It’s an effective bug killer and is so safe it’s often used to treat fleas, ticks, and other insects on pets.
It does have its drawbacks. Outdoors has a concise life, with warm weather reducing its effectiveness to a few hours. It’s also not great for pests with protective outer layers, like scale or mealy bugs.
But it’s a good option for hard-bodied insects like beetles, so it’s a solid choice if you have kids or pets.
2- Pepper Spray
No one likes their meal over seasoned, and insects are no different. A chili pepper tincture won’t kill your insect pests, but it will undoubtedly persuade them to stop eating the Hosta.
To make pepper spray:
- Simmer five tablespoons of hot pepper flakes in a gallon of water.
- Allow cooling overnight.
- Strain out the pepper flakes and add a few drops of dish soap.
Spraying over leaves will deter anything keen to take a nibble. It’s also effective on larger pests, like rabbits.
3- Herbal Tea
Another homemade spray is herbal tea – peppermint tea, to be precise. The fragrant compounds in peppermint deter insects, especially aphids. They can’t stand the smell at all.
While you can use a cup’s worth of fresh peppermint, a peppermint tea bag will work just as well.
Brew the tea as usual, and allow it to cool. Once it’s at room temperature, you can decant it into a mister bottle and apply it directly to the leaves.
4- Protective Covers
If you’d instead not spray at all, consider using a protective cover. A sheet of fine mesh placed over the Hostas will prevent most insects from setting up camp in the first place.
This is not effective for smaller insects like aphids, but if you have drama with grasshoppers, it’s an excellent way to protect the Hostas while you get the grasshoppers under control. It’s also good against small mammals like rabbits.
5- Mulching
I can’t emphasize how vital mulching is to the garden, and pest control is another excellent service mulches provide.
Many of the pests I’ve listed overwinter in soils, so a fresh layer of mulch in the spring will make it all the more difficult for the insects to emerge once the weather warms.
You can also replace winter mulches with fresh ones in the spring, removing the pests entirely.
When Not to Spray Bugs on Hostas
There are a couple of notable pests that are not worth spraying for.
First of these are slugs and snails. They love to eat Hostas, leaving ragged edges and holes rimmed with silver slime.
Sprays are largely ineffective against them, and you’re better off using a beer trap or an iron phosphate-based bait.
Leaf-cutter bees are another pest that does not respond to sprays. The female bees cut half-moon-shaped pieces from leaves to build their nests. Because they don’t eat them, they aren’t harmed at all by any sprays.
I like to leave them alone, as they’re an effective pollinator, but if you’d instead get rid of them, removing the nests will remove the bees, too.
Finally, not all bugs you see around your Hostas are pests. Plenty of insects eat decaying matter like much, so pillbugs, millipedes, and the like present no threat to the Hosta and can be safely ignored.