Box elder bug control recommendation

Asked February 27, 2017, 11:51 AM EST

What are the proportions of liquid laundry detergent and water for spraying box elder bugs? We have thousands (no exaggeration) that show up on 2 porches. They showed up about 5 years ago. We had never had them before. We don't have box elder trees or maples in the neighborhood that we can see. I do vacuum with a shop vac which helps some, but the numbers are overwhelming.

Clackamas County Oregon insect issues

4 Responses

If you are seeing box elder bugs aggregating on your home now (in the early spring), they are adults that have overwintered and are starting to disperse to host trees. During cool weather in the spring, the bugs will aggregate on warm, sunny southern / western walls of buildings, similar to what they do in the fall.

The bugs can fly several hundred yards (perhaps even a couple of miles) to reach overwintering sites. So it would appear there are host trees somewhere in your neighborhood and your house is in the vicinity of a good overwinter site. With that said, you may be able to kill many bugs with a soap spray, but that may not completely solve the problem because more may come from overwinter sites and congregate in the same place.

Soap works as a contact insecticide - it only kills those insects that are directly sprayed with it, So repeated treatments may be needed.

To make an insecticidal soap, mix 4 tablespoon of a dish soap (not a dishwasher detergent) per gallon of water. I would suggest spraying a small area of the surface you intend to treat to make sure there are no problem with the solution staining the surface. (if you can reach them, the shop vac treatment you are already doing may be just as effective as spraying them with soap).

As a final note, there are several insect species that aggregate in large numbers like the box elder bug. This webpage has a good picture of the western box elder bug If you are uncertain about the species identification, please take specimens to your local extension office for help with identification. Clackamas County Extension: 200 Warner Milne Rd, Oregon City, OR 97045, (503) 655-8631.

While I avoid pesticides in general, are there any relatively safe ones that could kll the box elder bugs? See also attached photos of top and underside. Not great shots, but best I could do today.

Are they eaten by birds or other critters?

And why have there been so many of these in the last 5 years? Have lived in this house for 40 years and didn't have them before. We live in Canby, Oregon 97013

Please also see previous question and photos I just sent.
Someone told me they have had a pest control apply an insecticide: /termidor SC Termicide Insecticide 9.1% along their foundation. They had issues with ants and box elder bugs.
Is this a good solution also?

Boxelder bugs are a type of stink bug, so their disagreeable odor deters many predators. Birds do occasionally take them as prey but not in significant numbers.

Whether it is worth treating for them with an insecticide is a judgement call for you. Boxelder bugs are a nuisance but otherwise are not harmful. Products like Termidor SC are designed for pest control around the exterior of structures and adjoining perimeter areas. Boxelder bugs tend to aggregate on light colored walls with a southern/western exposure – locations that receive a lot of sunlight. Sunlight breaks down the chemicals in insecticides so their residual effect declines rapidly so they stop working after a few days and additional applications could be needed. So you need to decide how much of a nuisance the bugs are and if that is worth the expense and trouble, and exposure of insecticides.

I would not recommend using insecticides indoors to try to kill bugs that get inside. It is difficult to get good coverage to justify the time and expense. Many of the ones that would be killed will die in inaccessible places, and their dead bodies will attract scavengers that create actual problems and more difficult to control.

As to why there may be more bugs in your area than in past years is probably related to environmental conditions. Populations tend to be higher in years with warm springs and/or hot, dry summers. I was recently in the Aurora area and saw boxelder trees and bugs, so it's not surprising that your neighborhood has them.