Knowledgebase

What's damaging my plants? #840840

Asked July 15, 2023, 4:55 PM EDT

Something is chewing the leaves of my serviceberry shrubs and also killing stems of my honeysuckle and butterfly weed. I think beetles or slugs may be eating the leaves but haven't seen them. Some type of larva may also be causing the stem damage. Any advice on mitigation is appreciated?

Baltimore County Maryland

Expert Response

A wide variety of leaf-chewing insects can damage foliage or flower petals in summer; they include many beetle species, caterpillars, sawflies, crickets, young grasshoppers and katydids, earwigs, and yes, slugs and snails. You might have to inspect the plants with a flashlight after dark to catch the culprits in the act, as not all insects are active during the day (or all day). Many also leave the plant to hide when not actively feeding, though you can look under the leaves for indications of any hiding there, day or night. If these plants happen to be near any outdoor lighting, like a street lamp, porch light, or accent landscape lighting, some beetles (like chafers and other scarabs) can be drawn to lighting at night, which can then bring them closer to attractive host plants.

We don't see Serviceberry (Amelanchier) in the photos but do see what appears to be Beautyberry (Callicarpa), though it won't matter much in this case as there are no serious leaf-chewing insect pests for either. (They can cause cosmetic damage like the notches pictured but nothing drastic enough to harm the long-term health of the plant.) You can pluck off any insect or snail you find chewing leaves but otherwise no action needs to be taken, and we especially discourage insecticide use on native plants that benefit our local ecosystem. If you want to make sure the culprit isn't a desirable insect first, you can send us close-up photos for an attempt at ID.

The stem dieback on the Bush Honeysuckle (Diervilla) is harder to diagnose and could be due to infection, root stress or dieback, or a stem-boring insect. We do not have information indicating they have any serious pests, but you can cut back the wilted and browned stems since they will not recover. Splitting apart the stem towards its base after removal might reveal tunneling or stained tissues that might suggest a borer or an infection, respectively. Here too, though, no intervention using pesticide would be recommended.

Butterfly Weed requires excellent soil drainage and may be prone to wilting if in a location that is kept too wet. If transplanted from one location to another recently, their taproot also has limited tolerance for disturbance, and this can produce wilting as well that the plant might not recover from. If infected with a root or crown rot, nothing can cure those diseases, so prune off wilted stems on this perennial or, if the entire plant is affected and the wilting can't be attributed to dry soil needing irrigation, then replace the plant instead.

Miri
Hi Miri,

Thank you so much-this is very helpful information!

On Mon, Jul 17, 2023, 12:57 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied July 17, 2023, 1:19 PM EDT

Loading ...