Herbs and Asiatic Beetles

Herbs are generally acknowledged to be some of the easiest to grow, most pest-resistant edibles on earth. At least, that’s what all the books said, and that had been my experience. Until last year.

It was about a year ago now that I noticed my basil was being eaten at a rather alarming rate. Leaves that were lush and fragrant when I went to bed were nothing more than a midrib with a few ragged shreds clinging to it in the morning. I inspected the plants carefully and kept watch for any voracious visitors for several days but saw nothing. Damage began cropping up on my mint and sage as well. Finally, I did an internet search and determined the cause of the problem – Asiatic garden beetles.

It was obvious they were the culprit, not just for their notorious taste for herbs, but because I had seen them everywhere. I had seen them in my shower in the morning, crawling on shop windows downtown, and dead on the sidewalks under the porch light. My first instinct was to take the advice I gave for years to callers on our radio show – handpick as many as you can. They are only active at night, so shortly after I started seeing their damage again this year, my husband and I went outside just as the sun was setting.

What we saw was frightening. Hundreds and hundreds of the beetles were emerging from the soil, congregating on the carrot tops, piling up on the petunias, and gathering through out the garden. And this year, since I had expanded my herb selection, they were really doing a number on lemon verbena and pineapple sage. We set out to squashing them and lost count quickly, but it would be no exaggeration to say that we each killed over 100. My husband stacked them carefully around the basil in an attempt to scare off their brethren (all that happened was we indulged thousands of very lucky ants).

And yet, the damage continued. Continues, excuse me. While I know that every female beetle I kill has an ultimate exponential effect on future populations, this is the first pest I have ever dealt with that I find completely discouraging. The things hide in the soil at night, so covering them with row cover won’t help. Systemics are out of the question – these are herbs, for pete’s sake – but every other night they come back in shocking numbers.

We’re still trying to figure out our control methods. In the meantime, we’re pretty darn adept at sqaushing beetles (and scrubbing black beetles guts out of our finger prints we finally do go inside to bed). If you’ve experienced this pest and tried a safe-for-edibles control that worked, I would truly appreciate your suggestions!

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