Jackie Bantle
Saskatchewan Perennial Society
While it seems that many insects are dying off or going into hibernation during the fall time of the year, there is one bug that has been coming out in droves over the last few weeks. If you have a female maple tree close by, you’ll definitely know what I’m talking about. And even if you don’t have a maple tree close by, these critters can still be a nuisance.
The insect that I am referring to is the Maple bug, sometimes called the box elder beetle and scientifically known as Boisea rubrolineata. The western maple bug is native to western North America and is related to stink bugs and cicadas, having piercing and sucking mouth parts. When crushed, maple bugs emit a bad odor. Apparently, they taste so bad that even spiders won’t eat them (unless they are desperate).
Adult western box elder beetles are flat and oblong in shape, 10-14mm in length. The main body is gray-brown to black in color with clearly visible reddish-orange lines on the thorax and wings. The body underneath the wings, which is visible during flight, is orange in color. The head and antennae are black.
The maple bug has 3 life stages: egg, nymph and adult. As winter approaches, adults look for crevices in trees and cracks in buildings to hibernate. In spring, as the temperature warms up, the hibernating adults emerge from their cracks and crevices. These adults feed on seeds and plants. They begin mating a few weeks after they start feeding.
In mid-July, box elder beetles move to female seed-bearing maple trees where they lay their eggs on trunks, branches and leaves. The eggs are small, rusty red and usually laid in groups of two or three. They may also feed and lay eggs on ash trees. Eggs hatch in 10-14 days and the nymphs feed on the seeds and leaves of the trees. There is no noticeable feeding injury to the trees. The nymphs start out bright red in color and change to black red as they grow larger. You can see bugs of all stages of development during the summer but there is only one generation per year.
As fall approaches and leaves begin to fall, the adult beetles look for warm, safe locations to hibernate for winter which is why you will often see hoards of maple bugs on the south side of buildings in fall. Box elder beetles are most abundant during hot, dry summers when followed by warm springs.
Maple bugs are not harmful but they are definitely annoying – especially in the fall when they gather around doors and windows to potentially enter your home. The best way to manage maple bugs in fall is to prevent them from entering your home. Repair or replace damaged window and door screens. Repair or replace damaged screens in the roof and soffit vents and in bathroom and kitchen fans. Any areas where cables, phone lines, dryer vents or other pipes enter your home should be sealed. Install rubber sweeps at the bottoms of all exterior entry doors.
If you have large numbers of bugs gathering around doors and windows, consider spraying soapy water directly on the bugs. Mix one tablespoon of Dawn dish soap with 1 litre of water and spray directly on the bugs. The dish soap will break down the oils and wax that cover the exoskeleton of the bug: the bugs dehydrate and die within minutes. To deter the bugs from coming back to these surfaces, wash the surfaces with dish soap and water or a scented cleaning solution.
Spraying with insecticides during the summer or fall is not recommended for maple bug control. Not only will you kill any beneficials that are present in the area, but maple bugs can fly for several kilometers from their source of food. Therefore, spraying in your yard will only delay the issue. Because the bugs are very mobile, getting rid of the maple or ash tree in your yard and your neighbor’s yard will also not solve the problem.
Maple bugs are something we need to exist alongside. Yes, they are disgusting, but they are not harmful and they will not kill your plants. Make Dawn dish soap and water your best friend during the fall and seal up the cracks around your home. Hope for a wetter summer and a cool spring and maybe they won’t be as bad next year. Happy fall!
This column is provided courtesy of the Saskatchewan Perennial Society
(SPS; saskperennial@hotmail.com). Check our website (www.saskperennial.ca) or Facebook page for a list of upcoming gardening events.
