7 Reasons Your Roses Have Holes in the Leaves
Did you spot holes in your rose foliage? Munched-on rose leaves are a common occurrence, but the guilty party varies. In this article, gardening expert and rose enthusiast Danielle Sherwood shares 7 reasons you might see holes in your rose leaves and what you should do about it.
It’s not wrong to want a perfect garden. Magazine and internet photos show colorful, beautifully formed roses on a spotless backdrop of shiny green foliage. Naturally, we want this for ourselves.
The truth is, we don’t live in an edited magazine. In real gardens, bugs coexist with us; some of them will snack on your rose bushes. A little tolerance goes a long way toward a healthy garden ecosystem.
How do you know when the holes and the bugs are a real problem? First, let’s assess the damage and determine if a good guy or a bad guy has visited your rose. Once you know who’s using your roses as a buffet, you can handle it accordingly. Let’s get started!
Rose Chafer Beetle
Rose chafer beetles, Macrodactylus subspinosis, are tan and appear somewhat fuzzy due to small yellow hairs that grow on their head and thorax. They are found in Eastern North America, preferring sites with sandy soil.
Rose chafers are normally around ½ inch long. They begin as fat white C-shaped grubs that overwinter in the soil to emerge in early spring. If you see one, there are likely more, as they tend to arrive in swarms.
Along with roses, they feed on many other ornamental plants and crops like strawberries, grapes, and peppers. They contain a toxin that makes them deadly when eaten by dogs, cats, and birds.
Rose chafers eat the leaves, buds, and flowers of roses. You’ll see large, irregularly-shaped holes on the foliage between the veins. They will eat a large amount, often fully skeletonizing the leaves. The beetles themselves are large enough to spot and can be found during their 3 to 4-week-long adulthood.
- If you have a small amount of affected roses, manual removal is the best option.
- Pluck them off and plunge them into soapy water.
- If they occur every year, consider erecting a cheesecloth barrier around your roses before they emerge in May or June.
- Purchase targeted sticky traps.
- Use an insecticide for large-scale infestations only if all other controls have failed.
Sawfly larvae, commonly called rose slugs, look like little green caterpillars. Their adult form is a dark-colored non-stinging wasp. They most commonly emerge in early spring when the weather turns warmer.
It’s critical to correctly identify sawfly larvae, as they resemble many other caterpillar species. Moth and butterfly caterpillars also eat roses, but they should be moved to another spot in the garden rather than destroyed. Caterpillars are the number one food source for birds and grow into important pollinators.
Newly hatched sawfly larvae like to chew on rose foliage, leaving tan, nearly transparent splotches called “windowpanes.” As they mature, they make irregular holes.
Look for tan “windowpane” blotches on leaves, along with larger holes. Turn leaves over and check the undersides for hairless green caterpillars with tan heads. They often congregate in groups.
- Prevent infestation by companion planting. Birds, lacewings, and ladybugs will eat sawfly larvae if you encourage their presence with a diverse array of plants.
- Manually remove them by plucking from leaves and dropping into soapy water.
- Insecticides are unnecessary and will kill their natural predators. The damage is rarely life-threatening to roses, so initial tolerance is often the best approach.
If you see tidy round notches at the edges of your rose leaves, you might have been visited by leafcutter bees. These beneficial pollinators are valued in the agricultural industry and home gardens. They are native to the Western United States.
Leafcutters are about the same size as honeybees. They don’t actually eat the leaves and they cause no lasting damage to your rose. Instead, they cut off small sections with their scissor-like jaws. They then roll leaves into a tube, fill them with pollen, and use them to line their nests.
I love seeing the work of these special bees in my garden. When I spy those half-moon-shaped notches, I think about how my roses contributed to a new generation of pollinators!
Leafcutter bees cut smooth round notches from the edges of leaves. The bees themselves are about ¼ inch and have furry black bodies with light banding. Instead of pollen sacs, the underside of females is covered with pollen-collecting hairs called scopa.
No fix needed! Leafcutter bees are valuable pollinators and should be encouraged in the garden. The leaves and rose as a whole will remain healthy. Enjoy the interesting hole-punched look and move along.
While usually a nemesis of the vegetable gardener, hungry slugs and snails sometimes strike roses too. Their damage is usually restricted to the lower leaves and canes, where they leave ragged holes and mucous trails behind.
Look for these mollusks at night when they are active. They prefer herbaceous plants over large woody perennials like roses, but they aren’t always picky.
Slugs and snails are gliding mollusks that leave slimy trails around their damage, which will look wilted and ragged. Slugs lack the external spiraled shell of snails but their bodies are otherwise similar.
- Place vertical copper screens around your roses.
- Clear any decaying leaves and sticks that provide moisture and shelter away from the base of your roses.
- Use beer traps (bury a cup to soil level and fill with beer. They will fall in.).
- Hunt for them at night with a flashlight and remove manually.
If you have Japanese beetles, you’ll know it! Unlike most beetles, they feed during the day. They are about .5 inches long, with sturdy, metallic green bodies and copper heads. The white tufts of hair near their legs are a distinguishing feature.
These invasive rose pests hail from Japan but are increasingly prevalent in the Eastern United States. Their white grubs spend winter in the soil and emerge to feast on turfgrass roots in spring. In early summer, they will pupate and take their adult form.
Japanese beetles eat leaves, buds, and blooms, causing significant damage to roses.
Look for skeletonized leaves. Rosebuds may be deformed, turn brown, and never bloom. Check open blooms for the beetles themselves.
- Use a bacterial control, called milky spore, in the soil to kill them in the grub stage.
- Manually pick adult beetles off roses in the mornings while they’re still sluggish.
- Interplant roses with alliums, geraniums, and catnip, whose strong odor repels them.
- Don’t waste time with insecticides or traps which have proven ineffective on Japanese beetles.
Fuller Rose Beetle
Fuller rose beetles, also called rose weevils, like to chew notches on the edges of leaves. You can differentiate their damage from that of leafcutter bees because their holes are ragged and irregular, unlike the neat, smooth-edged notches created by the bees.
These beetles are grayish tan, with noticeably pointed snouts characteristic of weevils. They are ⅓ inches long. They begin life as grubs in the soil, feeding on plant roots.
Fuller rose beetles don’t usually inflict serious damage and can be ignored in small numbers. They are prey for parasitic wasps and ladybugs.
These beetles are active at night. Look for chewed leaf margins with a serrated, jagged appearance. They burrow in the soil during the day and climb roses to feed at night.
- Wrap tape (sticky side out) around the base of your rose. They cannot fly and will be unable to climb past the barrier.
- Encourage their predators by planting companion plant attractants like alliums, yarrow, and sweet alyssum.
- Look for them in early spring (usually May/June) and manually remove.
- Build or purchase a ground trap.
While insect pests are the usual suspect, storm damage can take a major toll on roses too. Hail can cause holes in leaves, break fragile stems, and create cane wounds.
Keep an eye on the weather to avoid tattered leaves and lost blooms due to heavy hail. If a storm is coming, erect a covering to protect your roses.
Hail occurs most often in spring, but can accompany thunder storms any time of year. While normally pea-sized, the largest hailstones can reach the size of a golfball, inflicting serious damage.
- A heavy tarp held up by strong sticks and secured with stones will protect against hail in a regular garden bed.
- Roses growing along a wall or fence can be protected with large boards leaned against it.
- Cover small seedlings with an overturned bucket.
- Reinforce the strength of your primary rose canes by mounding soil at the base.
Most pests (and weather events) that cause holes in leaves are no cause for alarm. Identifying the cause will guide you to the best response. If a bug is the culprit, encourage natural predators and avoid insecticides whenever possible. They harm beneficial predators, create resistant pests, and damage the health of your garden.
Healthy and strong roses will be less susceptible to serious harm from pests or extreme weather. Companion plant, practice good pruning and watering, and enjoy your roses!