When something is munching your plants, it can be tricky to find out who’s the culprit. And determining the culprit is the first step in remedying the problem.
Below are some common Iowa leaf noshers with key elements that will help you identify them.
Slugs
Slug damage is extremely common in shady, moist places, especially during wetter springs and summers. Hostas are a notorious favorite.
- Often, at night with a flashlight or in the early morning hours, you can check under the leaves and see the slugs. They’re little tiny gray or pale beige soft-bodied slimy blobs, usually a quarter-inch or so long.
- Slugs often leave a shiny trail on plant leaves.
- On many plants, especially those with larger thick leaves, they make irregular holes with smooth edges.
- The holes are usually larger than a pencil eraser and smaller than a quarter.
- The damage also tends to be within the leaf blade instead of along the edges. (Most other chewing insects will eat from an edge and take much larger areas.) They usually leave the veins of the plant alone. Severe damage on a hosta will leae the leaves looking like Swiss cheese.
- On most plants, they seem to go for the nice, tender new growth.
- They usually stay closer to the ground and especially enjoy fruits and veggies that are lying on the groun, including as melons, tomatoes, or strawberries.
- Slug damage usually happens in Iowa from about late May onward. It’s too cold for them earlier than that.
- Favorite plants are, by far, hostas. But they like a wide variety of plants, including lettuces.
- Click here for a photo and more information on slugs and how to control slugs.
Rabbits
Rabbits can take just a few bites, nibbling on the most tender parts, or devour nearly the whole plant (as long as it’s tender and low to the ground.) Peppers or tomatoes have entire tops eaten off, with the stems and perhaps some of the tougher parts of the leaves remaining.
• Rabbits eat all or more of the leaf. They don’t leave tiny holes.
• Rabbits tend to do less damage to garden plants in late summer through fall, because they have so many different food sources and because most of our garden plants (that survived) are large and tough enough that they are less tempting to rabbits.
• Rabbits often leave droppings in your yard. They look like piles of tiny brown peas.
• Favorite plants include newly emerging tulips, pepper plants, green beans, and many annual flowers.
• Click here for tips on controlling rabbits in your garden.
Deer
With deer, damage is often up higher than rabbits or others pests might reach, as far up as 6 feet, since they’re taller animals. Rabbit damage goes only as high as they can stand, with or without snow, typically under 2 or 3 feet.
- Deer are messy eaters. They tear branches and leaves. Rabbits cut things off at nice, sharp angles.
- Outside of tall or electric fencing, the best way to deal with deer, if you have a problem with them, is to plant deer-resistant plants. Click here for a list of flowers and other plants that deer are less likely to bother. Click here for a list of trees and shrubs.
Other Wildlife
Sometimes, there is something else that is eating your garden plants. Often, simple observation and thinking through the problem can do the trick. Observe what size of animal did the damage, what they ate, and what the bite marks or nibbling patterns are and what sized mouth and types of teeth would create them.
- I have spotted a wood chuck who seemed to love nibbling just the edges of the my petunias in two large containers in the back edge of my yard. He also seemed partial to nibbling just the tips of some of the succulents in a dish garden. Even if I hadn’t seen him, I would have guessed that something about that size (and larger than a rabbit) was doing it.
- Possums love eating my fallen apples (they can have them–I’ve got plenty higher up). I’ve seen them at night with my headlights when I pull into my drive at night. During the day, I’ve seen rabbits nibbling on them, too.
- I think it’s a raccoon that emptied my little pond of its goldfish because the night they disappeared he knocked all the pots and tubing in it. Raccoons are one of the few garden pests that eat meat. I think he also is the one who raids my compost heap, and especially likes licking out the interior of egg shells (again, one of the few pests that eat animal products) and cleaning out the remnants of watermelon flesh from the rinds.
- The chipmunks were almost certainly the culprits uprooting my annuals in the pots in my front door because they made appropriately sized holes and sprayed dirt everywhere. (I put in pieces of chicken wire on top of the soil and solved that problem.)
Leafminers
- Leafminer damage is easy to identify because they make twisting, turning marks on the leaves. (Leafminers are the larvae of sawflies, which can cause a whole ‘nuther set of problems. See below.)
- The damage doesn’t usually don’t show up until later spring.
- Columbine, roses, mums, and tomatoes are a major favorite.
- Click here for University of Minnesota recommendations on how to treat them. (For what it’s worth, they do such limited damage in my Iowa garden that I just leave them alone.)
Other Insects
- The University of California has a great chart to look at that generally describes insect damage with lots of links to then find photos of the damage. Click here.
If you are really stumped by what type of insect is damaging your plants, consider submitting plant samples to the Iowa State University diagnostic clinic. Details here.