July 8, 2015

Slugs and Bugs – The Battle for the Garden

by Toni leland

It's that time of year again. Most of the country has battled weather beyond belief, and Mother Nature has played havoc with the growing season in many places. I mean, hostas blooming in New England in June?

I have written articles about slugs and Japanese Beetles (Popillia japonica) before, so rather than reinvent the wheel, I'll direct you to those articles for a deeper coverage of the subjects. But right now, my frustration with these critters requires a rant!

Slugs. They are disgusting and downright destructive. This year, they've taken on plants they would not have touched in the past. Things like marigolds. We plant marigolds to repel insects, not attract them! Sunflowers are usually left alone, but not this year. This past week, I've struggled to keep the ten sunflowers I planted, but one by one, the seedlings went down. The few that survived look as though they've been shot with BBs.

Sunflower damaged by slugs
Poor sunflower!

As a Master Gardener, I try to practice what I preach: use natural methods to protect the environment. I started with sand. Heavily applied around the base of the plants. Next morning, it was clear that hadn't worked! So I bought diatomaceous earth. It seems to work, but once it gets wet, you have to reapply it. So, every time I put some down, it rained. Plus, it is very unattractive to have your flower beds filled with snow white powder.

Okay, the old beer in a saucer trick. I never put much store in the idea, but I decided if it didn't work, I'd just drink the stuff and let the slugs have the garden. Check out my first morning's catch!
Slugs in beer
Slugs bellying up to the bar.






Of course, you have to dispose of the critters every morning, and keep the saucer filled. But it seems to be slowing down the damage. Maybe the sunflowers will win after all. (Unfortunately, the marigolds were so badly damaged, I doubt they'll do much more than die.) For more than you ever wanted to know about slugs, read my article Slug Those Slugs which also contains more ideas for control.

Next obnoxious and damaging pest coming up this month is Japanese Beetles. These beetles will strip a shrub or tree in a matter of days when the adults are at peak and breeding. I talk about the life cycle and susceptible plants in my article Visitors Without Visas: Japanese Beetles (Popillia japonica).

Japanese Beetle (Popillia japonica)
Japanese Beetle (Popillia japonica)
 One of the biggest controversies here is whether or not to use pheromone traps. Most Extension offices will tell you not to, as the scent used in the traps will attract beetles from blocks away. That's not what you want. Also, it's been stated recently that turf damage from the grubs is much worse in yards where the traps were used the previous year.

Personally, I watch carefully each morning to keep tabs on emerging adults. Hand-pick and destroy when there are only a few. If you have a huge number, then protect targeted shrubs with cheesecloth or row covers. The insects are highly active when it's around 85 degrees (F) and calm. Check with your extension agent for the recommended time to apply the grub killer. Most will advise putting it down at the end of July when the new eggs are hatching under the grass.

Oriental Beetle (Anomala orientalis)
Oriental Beetle (Anomala orientalis)


The Oriental Beetle is also showing up about now, but not in the huge numbers seen with the JB. The most damage is caused by the larval stage, which eats the roots of the grass. The adults feed on roses, phlox, and petunias.

Careful monitoring of your gardens each morning can save you a lot of frustration, and hopefully, a lot of plants.

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