This might just be the best horticultural news I’ve heard so far this year — the USDA is sponsoring research that shows fighting back against Japanese beetles may be as easy as adding a companion planting of geraniums to your vegetable patch or rose garden.

Standard, garden center geraniums apparently contain some sort of neuro-toxin that affects the beetles. A recent article in Agricultural Research magazine reports the following:

Within 30 minutes of consuming the petals, the beetle rolls over on its back, its legs and antennae slowly twitch, and it remains paralyzed for several hours. When paralyzed under laboratory conditions, the beetles typically recover within 24 hours, but they often die under field conditions because predators spot and devour them.

The poisoning effect of geranium flowers on beetles is not a new discovery; it has been reported in scientific papers dating back to the 1920s. But the phenomenon has not been studied in depth—how or why it happens—until recently, when Agricultural Research Service scientists in Ohio picked up where scientists left off more than half a century ago.

Scientists are now trying to isolate the compounds that paralyze the hapless beetles, so they can develop a natural pest control product. But really, doesn’t it seem easy enough to go with companion planting, if it turns out to work well? Geraniums are inexpensive and easy enough to grow in most places, and any sort of spray-on product that’s developed is likely to end up as one more contaminant in the water supply.

If you try this, please report on the results!