Beetle Battles

November 26, 2009 06:00 PM

Pam Smith, Farm Journal Seeds & Production Editor
The annual arrival of multi-colored lady beetles turned out to be more of an invasion this year. Our tractors were covered. So were the sides of our out buildings and my kitchen ceiling looks like a lady beetle landing zone.
I'm pretty tolerant of the "ladies” because I know they are an important predator of aphids and scale insects. However, their overwintering location (generally our homes) leaves a lot to be desired. The darn things aren't a bit appreciative of my hospitality either—their nip feels like a bite, although it doesn't break the skin. They let off an odor worse than my teenage son's dirty socks when disturbed and ooze a yellow-orange fluid that can permanently stain walls. Just when you think you've suck them all up in the vacuum, a sunny day comes along and they come flying around to pester you all over again.
Here we are in mid-November and I'm still battling these good bugs with bad social habits. So I went in search of some tips and learned that the best management recommendation is to prevent beetles from entering the house to start with. That put us busy as bees checking for seals and obvious cracks and spaces where beetles can gain access. Turns out that the attic window was a good entry point to my house—now if I could only teach these beetles to clean house!
It seems the vacuum is the still the best defense for in home invaders. I recommend emptying the bag to avoid the smell after you've had a roundup.
Chemical treatments can provide some protection, according to Ohio State University entomologists. The pesticide (usually a pyrethroid) typically is applied to outside walls and siding, as well as around eaves, attic vents, roof overhangs, and doors and windows. Pre-test a small area to make sure there's no staining or discoloration with the product. To learn more, read Ohio State's official fact sheet. Here are some other good sources of general information on these beetles: 
Ever notice there is a major amount of color variation within the lady beetle population?
  • Red color is due to high quality of food eaten as larva (i.e., lots of tasty aphids)
  • Yellowish color is due to fewer aphids consumed but more pollen as a larva 
  • More spots means lower temperature and a longer duration of pupa stage 
  • Fewer spots means higher temperature and a shorter duration of pupa stage

You can email Pam Smith at

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