Plant and Insect Diagnostic Clinic Update - September 29, 2010

The following are highlights and updates about samples and questions recently received in the Clinic:




Millipedes continue to migrate by the millions in some locations.  There are still no easy answers for control.  Sealing cracks and gaps to keep them outdoors is still the best defense against accidental invaders.  See our online Iowa Insect Information Note.


Speaking of no new good news to report . . . .  Boxelder bugs are back.  As usual, it will be worse for some people than for others, and the reason for the differences are still a mystery to us.  Prevent entry by sealing cracks and gaps.  Exterior sprays are available but of limited usefulness.


Speaking of accidental invaders . . . .  the prediction around here is that this will be a "low year" for multicolored Asian lady beetles because of the wet summer weather.  Oh, some people will still have more beetles than they can stand, but on average (for what that is worth) the numbers are expected to be lower than usual.  Stay tuned to see if our prediction is correct!


 If you have spent some time outdoors in the past few weeks you may have encountered one of our most vicious biting insect - the insidious flower bug.  This tiny insect has a bit that hurts!  Long sleeves are the best way to prevent them, traditional insect repellents do not work terribly well. For more information and a picture see our IIIN.


Yellowjacket wasps are more obvious now as their diet changes from protein to sugar.  From now to frost you can expect to see them at trash cans, in your soda can and lemonade (real sweetener only), on dropped candy wrappers, and at the hummingbird feeders.  There is great debate whether hummingbirds are intimidated and kept from the feeder by wasps.  Apparently some hummingbirds are more easily dissuaded than others.  There is a "fix" that will reduce the ability of yellowjackets and other wasps to drink from your hummer feeder:  "Bee guards" or tube extensions for your feeder may be available at the bird seed store.  See the Hort Newsletter from July, 2000 for more details. 


Speaking of wasps, yellowjacket wasps and their close relatives the baldfaced hornets make nests of a papier-mache' like material manufactured from wood fibers and wasp spit.  The wood fibers come from dead limbs and exposed, weathered lumber such as fence boards and deck railings.  See the photo below.  The damage to fences and decks is cosmetic and usually not significant.  Tolerate the chewing damage for a little while longer; yellowjacket wasps and hornets die when it freezes.  Alternatives for your deck railing are to stain or paint, or cover with hardware cloth or chicken wire till the hornets are done for the year.


Hornets and yellowjacket wasps obtain wood fibers for their nests from weathered lumber such as deck railings.  Photo by Jim Dowie.

Hornets and yellowjacket wasps obtain wood fibers for their nests from weathered lumber such as deck railings. Photo by Jim Dowie.


Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on September 29, 2010. The information contained within may not be the most current and accurate depending on when it is accessed.