Ladybugs are some of the most recognizable insects, known for their distinctive dome shape, orange-red bodies, and black spots. In Canada, the primary distinguishing feature among different ladybug types is the number of black spots on their wing covers, with variations such as the two-spotted and thirteen-spotted lady beetles.
Multicoloured Asian lady beetles, a specific ladybug species, were introduced to North America in the 1970s to combat aphids and other crop-damaging insects. Their rapid reproduction and ability to endure harsh winters have made them one of the predominant ladybug species in Canada. These lady beetles are slightly larger than native species, typically measuring between 6 to 10 mm (.24 to .39 inches) in length. They exhibit a range of colors from mustard yellow to dark reddish orange, with varying numbers of black spots on their wing covers, and some individuals may have no spots.
The multicoloured Asian lady beetle also features two white oval markings on either side of its head and often displays an M-shaped marking just behind its head. Their bold colors serve as a defense mechanism, warning birds and other predators that they are unpalatable.
Ladybugs are among the most beneficial insects, serving as voracious and efficient predators of insect pests. They feed on over 50 aphid species and are a valuable asset for safeguarding home gardens, commercial orchards, and vegetable crops. Importantly, ladybugs do not sting, transmit diseases, or infest food supplies. Of the over 450 ladybug species in North America, only three types feed on plants.
However, one species, the multicoloured Asian lady beetle, has become increasingly problematic. These ladybugs tend to congregate in large numbers in the fall, seeking a safe and dry location for the winter. Attracted to sunny exposures on homes and buildings, they cluster on exterior walls and eventually find their way indoors through cracks and openings. Their sheer numbers can be a significant nuisance for homeowners, particularly those living near fields or forested areas.
Ladybugs can live up to two or three years under favorable conditions. During hibernation, they rely on stored fat for sustenance.
After clustering on exterior walls, ladybugs gain entry into dwellings through gaps in doors and window frames, eaves, utility openings, foundations, and wall siding. Once inside, they become disoriented and gather on walls, ceilings, and around windows in search of an exit. While most of these stragglers perish within a short period, others may find a safe place to hibernate in attics or wall voids, emerging occasionally during mild weather.
A larger influx can be anticipated for several days in late winter or early spring when they leave their winter hiding spots to venture outdoors for mating.
Ladybugs produce multiple generations each year. Adult females lay clusters of 10 to 50 tiny light yellow eggs near aphid colonies. The larvae (hatched eggs) are spiny, mostly black with orange stripes, resembling tiny alligators. These larvae share the adults’ insatiable appetite for aphids.
Preventing ladybugs from entering buildings is the most effective method of control. Sealing gaps, cracks, and installing weather stripping can keep them outdoors. Pay particular attention to the sunny, southwest sides of your home, as shady areas are less affected. Repair screens, caulk windows and door jams, seal cracks and crevices in the siding and foundation, and plug holes in roofing, vents, and attic walls. Inspect and seal gaps in service utility entrances.
Once ladybugs have infiltrated your living space, there are limited treatment options. You can sweep or vacuum them up and dispose of the bag to prevent their return to your home.
Currently, no pesticides are registered for ladybug control. For professional ladybug control in Edmonton, rely on Classic Pest Control Edmonton.