Japanese beetles feeding on Knock Out rose
Every morning for the past week and a half, my day has started by making the rounds of the garden in search of Japanese beetles. These voracious pests prefer the roses in my garden, but I’ve also found them on raspberries, hydrangeas, asparagus, and hibiscus. And I’ve seen evidence of their feeding on chokeberries and cannas, too. They can feed on more than 300 species of plants, so they may choose others in your yard. At other locations I’ve seen extensive leaf feeding on grapes, golden rain trees, and lindens. Most feeding injury occurs on plants in full sun. Damage can quickly mount up because as the beetles feed, they give off a pheromone that attracts other beetles to the site. That’s why you’ll often find clusters of them feeding as on the Knock Out rose pictured above.
Damage to foliage is characterized by leaf skeletonization. The beetles eat the “good stuff” and leave the tough veins behind. Lower on the same rose plant I found the skeletonized leaves pictured below.
Leaf skeletonization from Japanese beetle feeding on rose
Rather than allowing the beetles free reign of the yard, I fight back with a bucket of soapy water. The beetles have the curious habit of dropping off their feeding site when disturbed before flying away. This trait makes it fairly easy to hold a small bucket with several inches of soapy water (I use liquid dish detergent) under the flower or foliage being devoured, and with a light brush of the hand, sweep the beetles into the bucket where they meet a quick demise.
In the grand scheme of things, collecting Japanese beetles every morning during their month-long feeding cycle may not put a noticeable dent in the population (unless you can convince enough of your neighbors to join the attack), but it feels better to be doing something to thwart their actions than to give in to their appetites. And I have to think that eliminating hundreds of hungry beetles at least does a little good. If nothing else, I get the satisfaction of seeing a bucket full of dead beetles!
A morning's harvest of Japanese beetles
For a list of plants that Japanese beetles tend to avoid, and more control tips, read our online story about Japanese beetle control.