DEAR SUN SPOTS: I was concerned by your response to the gardener who wanted to keep Japanese beetles off her rose bushes. It’s important for home gardeners to be aware that we are currently in the midst of a worldwide die-off of insects so severe that many scientists are referring to it as an “insect apocalypse.” It’s also important to realize that life on Earth, including human life, depends on the work of insects. Any treatment to kill grubs in the soil will likely kill not just Japanese beetle grubs, but also grubs of many other beetles and perhaps also larvae of ground-nesting pollinators like native bees.

A more ecologically sound way of controlling those annoying Japanese beetles is to drown them before they have a chance to reproduce. I keep a covered container with water and a little bit of dish detergent near my rose bushes (I use a quart yogurt container), and each day during the beetle season, I spend a few minutes knocking beetles off the roses and into the container. It doesn’t completely eliminate them, but it does greatly reduce their numbers and the damage to plants. — Ecological gardener, Poland

ANSWER: Thank you for this important information. It is indeed a far better solution. We also got this great advice:

DEAR SUN SPOTS: Japanese beetles! They are a problem here in Litchfield for years. I haven’t had much success with traps, but I had a great deal of success with them this year. The beetles destroy my raspberries. I learned that by using a quart spray bottle with two ounces of olive oil and the remainder with tap water, sprayed directly on them, it immediately disables them, and they die within 5-10 minutes. The main issue with the solution is water and oil do not mix, so I needed to constantly shake the container. Supposedly, a drop or two of dish detergent will emulsify the oil with the water, but I didn’t like the idea of my berries tasting soapy.

Another method that works well is a container of soapy water and early morning or evening, flicking the pests off into the solution. That’s the end of them. My next attempt is applying nematodes. They destroy the grubs before they hatch. Supposedly they work well but timing and cost are big considerations.
Pesticides like neem oil work, but one must be vigilant. Other insecticides work but be sure they’re safe for bees. The beetles do not travel very far in their life span, so traps don’t want to be used too close to plants you want to protect or so far away that they won’t be drawn to it. The internet has lots of good information. When I checked for the latest this morning, I found vegetable oil also works well. — Cal Brown, Litchfield

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