Japanese Beetles

Friday, August 2, 2013

Just in from a morning walk with Karl the Wonder Dog. It rained a little during the night and the skunks came by to work on our lawn some more, looking of course for Japanese beetles that are coming to the surface to begin adulthood on the rugosa roses.This is August and in Vermont this is when the biggest hatches occur. I say "hatches" which is really not correct but this is the time when soil temperatures rise and adult beetles emerge from the soil to feed heavily on plants they like. Gail has 5 varieties of rugosa rose we brought from Burlington when we moved here and they are big roses now and the beetles love them. But they like our grape vines and our hollyhocks and in a drier year, the zinnia crop we grow for cut flowers. They also seem to prefer the lighter colored daylilies we have growing in sandy soil when they set up residence  in the fields.

Japanese beetles have been around since about 1914 in America when they are believed to have arrived  mixed in with a shipment if irises. Documentation on when certain insects arrive is always a problem because it's likely that bad insects arrive some time before they are noticed. Asian longhorn beetles, the emerald ash borer and the lily leaf beetle all have varying dates of arrival but unlike people type immigrants there is no clearing house upon their arrival and they seem to get established all too soon. Right now the state of Oregon is waging a giant battle against Japanese beetles because they figure the beetles cost their nursery growers $33 million per year. I suspect the actual figure is higher. The impact of this particular insect is even greater than state by state losses as Cornell University did a study and determined that they are also responsible for 40% of the threatened/endangered plant species in America. This is a little insect that has enormous influence.

Control is always possible but there is coast to coast debate on the best way to slow down the pest. I go with organic as my experience is that organic compounds such as the bacteria known as milky spore really work very well and do nothing to injure or kill other insects such as my honey bees. There are also nematodes that work very well but I think take a little longer to get established than milky spore. Others do not agree with either and feel that more harsh chemicals such as Sevin have to be used so you can visualize the death of the insects and know that you're eliminating the problem. I don't like to get to that point.

The state of Oregon uses traps scented with pheromones but these are a nuisance to me for a variety of reasons. If you do not have a big beetle problem, you will have as the pheromone is so strong that it lures in beetles from as far as 3-4 miles away (University of Vermont study). Seems to me a person would have enough trouble in their own backyard without enlarging the territory they are drawing bugs from. On top of that, what do you do with the bag full of beetles when the trap is full? And finally, here in Vermont as example, we have a big, big, big problem with black bears. They love beetles and while visiting your home they smell the bags of trapped beetles and sit on your lawn ripping open the bags and feasting--hence another mess and another even bigger challenge--how to tell the bears you do not trap beetles any more?

Milky spore is available in garden centers and box stores. It looks like talcum powder when you open the can or bag but the bacteria is really there and it really works. It should be applied to the soil prior to or during a rain so it can get into the soil and then it attaches itself to beetle grubs. Once infected the grubs die and become another source for the bacteria to grow in. It takes some time to establish in your lawns or fields but once established you will see the difference. You'll know you are successful as Spring arrives and signs of moles rototilling your lawns are finally absent. No grubs, no food source for moles either and they move someplace else. Give it some thought, give it a try.


Writing from the mountain above Peacham Pond where it just started to rain again. It's 58.8° this morning. I hear a loon calling from the pond suggesting I guess that I get moving. Lots to do at the flower farm. Rain or shine, stop by and say hello. The daylilies are very special right now and I have to say I am really enjoying the opportunity to meet new gardeners from around the world as some report  they are a Facebook friend and others explain where they live. Maine is always very well represented but yesterday three cars were from Michigan. Fun! Interesting!

George Africa
The Vermont Gardener
Vermont Flower Farm
On Facebook as Vermont Flower Farm and Gardens (Like page) and also as George Africa
On Twitter as vtflowerfarm
Always here to help you grow your green thumb!

George