I drowned my first JB yesterday, June 19th, and my second today, on June 20th. This is at least a week earlier than last year and a good two weeks earlier than previous years, when we anticipated their arrival around the 4th of July. This is likely the result of climate change and probably portends that JBs will find their way further north in Minnesota (and in states like Wisconsin and Michigan), compared with last year.
Here's an excerpt from my 2015 blog "The Beetles are Coming! The Beetles are Coming!" discussing that phenomenon:
It's interesting that there seems to be a north/south line of demarcation in the Twin Cities for JBs. We live in the southwestern part of the metro area and have been seeing JBs for just the last six or seven years, peaking in 2012, as our winters have become less severe, statistically moving us into the range of USDA zone 5. Most gardeners in the northern suburbs, roughly 10 miles from us, as well as gardeners in St. Cloud, northwest of us, have never seen JBs. That would indicate that JBs are harbingers of climate change, as are many other insect species. Since 2012, we have had lighter infestations, until this year, which is quite heavy, approaching the levels of 2012, at least here in Edina.
I'm virtually positive that folks will see them further north this year, given their earliest-ever arrival here. I will be very interested in receiving confirmation of my prediction. (In the last few days, I have received reports from two rosarians, one in a northern suburb, Andover, and another way up north in Fergus Falls, of large black beetles that look a little like JBs, but are the wrong color and definitely not the monsters). Please don't be shy in reporting and send cell phone pictures, if you can, for confirmation.
The most important thing to know about controlling these monster buggers (which I hate so much) is that trying to use insecticides in the average rose garden is the wrong approach, because you will kill virtually all of the beneficial insects in the garden at the same time, including, most importantly, lady beetles and bees, while the JBs just keep on coming from several miles away. The right way of controlling JBs is to patrol the garden each day (morning and evening are best because they're sluggish) and drown them in a can of soapy water. It's a daily job, but it's effective because JBs have a dropping instinct that makes them vulnerable to falling into the water.
Here is my complete discussion from last year's blog, which tells you everything you need to know about JBs for 2016:
Here, also is my May 2016 presentation to the Minnesota Rose Society on pesticide-free rose gardening, which contains several useful slides about JB control:
I would say "enjoy" but this ain't enjoyable. Good JB Hunting and please keep me posted.
June 20, 2016