The Q&A Archives: Perennial Leaves Eaten

Question: Leaf holes (eaten leaves) are affecting my purple and white coneflowers, black eyed susans, and the amaranthus (loves lies bleeding). I set out beetle traps and they appear to be working. Is it possible that ants can be causing the problem also? I sprayed some dursban, ant, flea, and tick killer (plus many additional pests) around the flowers today. Was this a mistake? I am afraid to spray anything that will kill the flowers. Can you give me some advice?

Answer: Generally speaking, the plants you are growing have very few pests with the possible exception of Japanese beetles and perhaps an occasional aphid. While the beetles cause unsightly damage, they usually do not kill the plants. Some gardeners simply tolerate the damage for the duration of beetle season; in my experience, some years are better or worse than others.

If the infestation is very heavy, traps are one possible method of control. The traps do catch beetles, but they also attract them to the area with the pheromone lure. Be sure you have positioned them according to the label instructions so that you are not inadvertently attracting them to your flowers. Another method of beetle control is hand picking or knocking them into a container of soapy water; if that is too time consuming, regular applications of neem according to the label instructions should help.

To be honest, I doubt that ants would cause any problems for your perennials. (Ants are actually useful in terms of the soil and it's health.) If you are seeing ants climbing up on your plants, it is possible they are there to "milk" aphids. If you look closely at the new growth you may find some aphids (very tiny, soft bodied sucking insects) there. Aphids can be easily knocked off with a firm spray of water from the hose. Often, ladybugs and birds will also appear and help get rid of them.

Usually, it is a good idea to use the least toxic control that is effective for the problem you have. So in general, before you use any type of spray or dust in the garden you should first verify what you are trying to control, then read the label carefully to be sure that it is effective against the pest in question and that it is safe to use on the plants you have. While the labels are long and detailed, they are also very informative. And please, always read and follow the application instructions -- very often the product will not be effective unless it is applied correctly.

Good luck with your beetles. They are just appearing in my garden, too.

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