By Linda Williams, forest health specialist, Woodruff. Linda.Williams@wisconsin.gov; 715-356-5211 x232
In the December 2017 edition of Forest Health News, I wrote about ladybugs congregating in or on homes during autumn. Now that winter has finally ended in Wisconsin, ladybugs that spent winter in the walls of your house are emerging, and many of those will accidentally emerge into, not out of, your home. This can create panic or aggravation, depending on you (or your spouse’s) tolerance for insects in the house.
So, what can you do? And what can you do to prevent this problem in the future? For now, you’re stuck trying to remove the ladybugs from your home. You can kill them or release them outside, but try not to crush them as they will stain your wall/carpet orange. One option is to vacuum them up daily, but then you should empty the vacuum bag/canister every day, otherwise they’ll start to stink and the smell will permeate into your vacuum cleaner; you’ll forever after smell dead ladybugs when you vacuum. Another option is to gather up and place the ladybugs into a container filled with soapy water, which will kill them. Just place the container under the insects and flick them in using your finger, a toothbrush, etc. They will drown in the soapy water and you can then dispose of them. You’ll have to do both of these methods daily this spring until the ladybugs are gone. You could bug bomb your house, but that will only kill ladybugs that have already emerged and won’t get into the walls where there may be more waiting.
To prevent a future problem, you need to prevent ladybugs from congregating or entering your house in the fall. Pesticides can keep them away at the time of congregation, or you can “build” them out of your house by sealing all holes and cracks. If you choose to spray your house, timing can be important. Ladybugs start looking for a spot to overwinter right after there is a good frost/freeze event in the fall followed by warm sunny days – this is the period that they will start congregating. Typically, you will need to have your house sprayed by the first week of October. Depending on the length of the fall season and the product used, you may have to reapply the pesticide. More information on products to use and ways to exclude the insects from your house can be found on the UW Extension ladybug page.