Monday, July 28, 2008

Meet the beetles

This damage was caused by the iridescent, metallic green Japanese beetle. The population of these pests has grown unchecked since they arrived in the state of Illinois several decades ago.

The adults eat the leaves of birch, linden, fruit trees, roses and purple-leaved shrubs, of which I have several in my yard. Check that – had – in my yard. A purple leaved sand cherry bush is now mostly twigs. The roses were history weeks ago - discovered when we returned home from vacation. A birch tree in my front yard has shed several lawn bags of leaves rendered useless by the beetles’ feeding, despite regular sprayings of insecticide. Dead beetles rain from the tree after each spraying, but are soon replaced by new beetles from elsewhere. A neighbor with a fruit tree has beetles by the hundreds infesting his yard.

If you have a Japanese beetle problem the best thing to do is to spray affected plants with chemical products available at most home stores, such as Sevin, Bayer Advanced Multi-Insect Killer Concentrate and Ortho Bug-B-Gone. Pheromone-activated beetle traps can be used to good effect – a neighbor has captured and disposed of several plastic bags full of the insects over the past week or so.

This is also the time to treat your lawn to kill the grubby offspring that the bugs are producing. Milky spore powder will kill grubs and eggs before they become a problem next year.

Click on pictures to enlarge. Photographs © 2008 James Jordan.


phule said...

[[Pheromone-activated beetle traps can be used to good effect – a neighbor has captured and disposed of several plastic bags full of the insects over the past week or so.]]

As both links point out, this is not a solution.

Pheromone bags /attract/ beetles. From long distances. (Japanese beetles can fly up to 2 miles at a time). Placing pheromone bags out only brings in more beetles than you had. It exacerbates, not solves, the problem.

An application of Merit to the roots of your affected trees in the spring (before leaves are produced) is a solution to spraying insecticides (and is certainly better than the traps). The leaves that are produced are poisonous to the beetles and they die, limiting damage to the trees.

However, this (as we have found out) replaces piles of dead leaves with /huge/ piles of dead beetles.

Merit is not a perfect solution either because the tree may not take up the Merit equally in all parts. You may end up with patches of dead leaves or even half a tree consumed with the other half green.

Defoliation by the beetles, generally speaking, is not harmful (long term) to trees. It certainly looks ugly and makes a mess.

James said...

Phule, thanks for the thoughtful comment.

Yes, the linked article pointed out that there were downsides to the traps. In my case, Ive noticed a decrease in the number of bugs in my yeard since he set out his traps. My loss, his gain.

Thanks for the tip about spraying the roots. That's something that I'm going to try next spring. It sounds as if you speak from experience.

We're planning an open house for next July (wedding-related) and I think that I'd risk a layer of dead bugs over dead leaves.

n8 said...

Thanks for the tip on Milky Spore. We have a problem with Japanese beetles on our grape vine. It's quite a nasty site.

Wanda said...

That is one hungry beetle!!