I’ve gotten a lot of questions about bugs eating plants lately. Some are very specific, listing the plant, the damage and a description of the pest. Others offer much less information. So I’d like to address the common pest today.
First, if you are an experienced gardener, you know that no garden is — nor should it be — bug free. Many are beneficial as pollinators, others control the pest population and still others are just pests.
What kills your pest probably will kill others as well, particularly if you use a non-specific treatment such as an insecticide. Some problems are just short-term — a week or two of feeding and the insects move on or move into another life stage. This sort of thing is best treated by maintaining strong, healthy plants that can easily survive the attack.
When approaching any garden problem, the first and most important aim should be the correct identification of the offender. Some preliminary diagnoses are quite simple. What is the damage and can you see the pest? When are the plants attacked? At night or at a particular time of season? What do they attack? Leaves, buds, stems, flowers, roots?
So lets look at a recent letters:
Q: Can you help me? My hibiscus plant leaves are being eaten by a pesky bug. What can I do to stop that from happening?
— Kadee Brown
A: Kadee has identified the plant and the site of the attack but has not described the damage. Are the leaves eaten from the edges, are there holes, are the leaves skeletonized? Nor has she given any clues about the pests. Has she seen them? Are they caterpillars, beetles, ants?
With this information, I can make a guess but the list of suspects is long: aphids, mealybugs, thrips, sawflies, whiteflies, spider mites or Japanese beetles. Each does its own type of damage and requires a particular control method. The best course is to ask a few more questions, so I asked Kadee:
Have you seen the pests? Are they caterpillars, beetles or something else? What kind of damage are they doing? Eating from the edge of the leaf, eating holes in the leaf? When does the damage occur? Have you checked under the leaves? Is there any webbing, sticky goo, black moldy stuff, tiny piles of debris, either from chewing into the plant or bug poop?
When Kadee responds I will be able to give her a much better answer.
What else eats petunias?
I recently addressed a problem with small worms eating petunias and taking on the color of the flowers. That problem turned out to be the tobacco budworm. However, other gardeners have different pests in their petunias. In a very short and direct note, Barbara Rumsey offered her observations:
“Your petunia-eating column: Slugs eat mine.” — Barbara Rumsey, Quakertown
I also have petunia-munching slugs but since my petunias are in containers, I can control the problem by edging my boxes with copper tape and keeping them spaced apart so that there are no moist, shady paths to the pots.
Dill or parsley for butterflies
While not a question, reader Carole Mebus noted that the black swallowtail caterpillars ignored the parsley and ate the dill:
“This year I planted a pot of dill for the black swallowtail caterpillar since dill is one of the food plants…
