One of the worst garden pests out there, IMO, is the Japanese beetle. And it’s Japanese beetle season again (sigh). You West Coasters can count yourselves lucky. All of us east of the Plains, buckle up.
In the immature stage, we know them as grubs, the kind that attack your lawn. It’s actually pretty easy to keep them out of your turf. The problem is that the adult beetles are very good fliers, and can travel miles. And they have a seemingly supernatural ability to find the foods they love. So regardless of what you do to prevent them in your own yard, you’ll still have to deal with the hordes that zoom in from surrounding areas.
Contech Japanese beetle trap
There are two things you can do: spray the plants they favor (beans, linden trees, wisteria, hibiscus, and rose, to name a few on a very long list); and use beetle traps. Actually there’s a third thing: many recommend knocking the beetles by hand into a bucket of soapy water. Conceding that the soapy water DOES work on the few dozen or hundred that you might actually succeed in capturing, that still leaves the other 4,568,342,721 to deal with. If you have a mild infestation, you’re lucky, and soapy water might be a viable solution. If you have a bad infestation, well, you know what I’m talkin’ about. Call out the bombers. Or move to another state.
What I’ve started doing is using traps. I know of the research that says they draw in more than they actually catch. But in my case, I’m not so sure. I know this much: when I DON’T use a trap, the beetles do a number on my garden. When I DO use a trap, there’s still a goodly amount of damage, but I think it’s a little less. It certainly isn’t any worse. Meanwhile, as I see it, every beetle in that trap is one less that’s out eating my green beans, and laying eggs for next year’s hatch.
I have used several different traps. They all work. In fact, you would not believe how they pull in beetles! They use a pheromone that gets the beetles in the mood, if you know what I mean. So that would explain why they’re so effective.
It’s what happens after that that sets the traps apart. You see, these things can catch a LOT of beetles. So the capacity of the trap becomes a pretty big deal. But another issue is how easily the trap empties (because they do fill up). And yet another issue is ventilation and drainage holes. Guess what happens when it rains and you get a pile of dead beetles fermenting in warm water of the bottom of a bag? Yeah, it’s as repulsive as it sounds. You better have a cast iron stomach if you want to clean that out without wretching. So…..that’s a problem.
All things considered, the trap I like best is a Contech model. The plastic basket unscrews easily, is vented and drains (not perfectly, but well enough), and it’s heavy enough that it doesn’t flap around in the breeze (which is another thing I don’t like about some other brands). The big problem is its capacity. Often, I come home to an overflowing trap. The other day, I decided to keep emptying it, all day long, to see how many beetles it could capture. And the total was (drumroll, please): 3.4 pounds. Yes, seriously, I weighed it. If the trap could hold a gallon of beetles, it would be the perfect unit. Unfortunately, it only holds about a quart. You can’t have it all, I guess.
3.4 pounds of Japanese beetles -- One day's haul
This all leads to a problem I never considered until I started trapping beetles. What do you do with them all? First you have to kill them. If you don’t, they eventually escape from whatever you hold them in. Usually, a few minutes on hot pavement does the trick if they’re trapped in a bag. Unfortunately, once they’re dead, they stink. Bad. So I have started keeping them in plastic bags on the ground outside our garage (so they don’t smell it up), then I throw them away on trash day. The wife wasn’t real happy about bags of beetles sitting around. She reminded me that our neighbors are trying to sell their house, and bags of dead beetles in the yard next door might be an impediment. Could be she has a point.
But the dilemma remains: what the heck do you do with 20 pounds (a weeks harvest, give or take) of Japanese beetle carcasses? There’s no easy answer.
All I can say is, thank goodness beetle season only lasts a few weeks!