ASIAN LADY BEETLE
These ladybug look-alikes hibernate in our homes over the winter- why can't I do that?
What do Asian Lady Beetles look like
Have you ever noticed clusters of "ladybugs" gathering around your windows? They’re not ladybugs, they're Asian lady beetles! Asian lady beetles are oval-shaped insects that can grow up to 8mm in size. They come in a variety of colours, including tan, orange, and red. Their wing covers feature up to 19 black spots that range in size, shape, and opacity, though some may have no spots at all. Generally, females are more likely to be multi-spotted, while males tend to be the ones with fewer or no spots. Asian lady beetles are often mistaken for ladybugs, but there is a very distinct feature that set them apart. The key difference is the M or W-shaped marking on their thorax, just behind the head, which is unique to their species.
A spectrum of spots & shades
Where do they live?
During late spring and summer Asian lady beetles thrive outdoors! They nest in gardens, forests, farms, and agricultural crops - particularly soybeans and corn - as well as in ornamental plants like roses and sunflowers. However, as temperatures drop these beetles seek shelter indoors to hibernate over the winter.
Seasonal Invaders
From September to November, Asian lady beetles begin invading homes and buildings in search of a safe, warm place to hibernate. They enter through cracks and crevices around door frames, windows, soffits, and behind fascia boards. Throughout winter, they remain mostly dormant in attic and wall voids, waiting for the return of warm temperatures and sunshine, though the odd one may escape into the living areas of the home when the heat is on. The most effective time to do treatment is in the late summer and early autumn, preventing the Asian lady beetles from overwintering in your home.
From March to April as the weather begins to warm up, they awaken from their slumber, and attempt to escape to the outdoors. This is when homeowners begin to notice them gathering around sunlit window sills, doors, light fixtures, or wandering around disoriented while making their way outside. Because nighttime temperatures are still too cold for the beetles to survive outside, they re-enter the home overnight. This cycle continues until conditions outside become consistently warm and can they remain outdoors full-time. We are able to do treatment in the spring to eliminate Asian lady beetles that have hibernated in the home over the winter, and prevent them from re-entering during the cold spring nights.
What do Asian Lady Beetles eat?
Asian lady beetles primarily feed on aphids, mealybugs, mites, and other soft-bodied insects. This makes them beneficial to farmers and gardeners, as they help control pests that can damage plants and crops. Their presence is especially advantageous for soybean and corn farmers, but fruit farmers may not share the same positive experience. Asian lady beetles are known to nest in and feed on soft, ripe fruits, with grapes and raspberries being among their favourites.
Did you know?
Adult female Asian lady beetles can consume up to 75 aphids a day, while the males may consume up to 40. Females could eat around 5,000+ aphids in their adult lifetime!
Spot the difference!
Asian lady beetles and our native ladybugs look strikingly similar, there are key differences in their appearance and behaviour that set them apart.
Colours & Patterns
Ladybug spots are symmetrical on each wing
Colour range is limited to dark orange to bright red
Black spots are solid black and circular
The area behind their head is mostly black, with white patches on the side. No distinctive markings
Native ladybugs
Asian Lady Beetles
Asian lady beetle spots are often asymmetrical, irregularly shaped, faded, or even missing altogether.
They have an assortment of colours which range from yellow, brown, orange, and red
They have a unique M or W marking behind their head. This is a feature other species of ladybugs do not have
Slightly larger in size compared to native ladybugs
Winter Habits
Despite their similar looks, ladybugs and Asian lady beetles react very differently to cold weather:
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Ladybugs: Native to Canada, they are cold-tolerant and overwinter outdoors. They shelter under rocks, tree bark, leaf litter, or in tree cavities to hibernate.
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Asian lady Beetles: Cannot survive temperatures below 5°C, and are not adapted to Canada's cold winters. To survive the winter they seek warmth indoors, and hibernate in attic and wall voids. They return outdoors in spring when temperatures are suitable.
are there risks of Asian Lady Beetles?
1.
Threaten native ladybug species
At first glance, Asian lady beetles may seem relatively harmless. They don’t spread disease or cause structural damage to buildings. While they pose no direct threat to people, they are a danger to native ladybug populations. Originally from Asia, Asian lady beetles are classified as an invasive species. However, they were not accidentally introduced - they were intentionally brought to North America in the 1960s and 1990s as a natural method to control agricultural pests like aphids. While they proved effective in reducing aphid populations, their own numbers quickly spiralled out of control. They were first reported in Canada in 1994 and have since become the dominant lady beetle species across North America, out-competing native species. Native species, such as the nine-spotted ladybug and the transverse ladybug, are now endangered, and in Ontario they are on the verge of extinction. Meanwhile, Asian lady beetle populations continue to grow, further threatening biodiversity.
2.
invade in large numbers
Asian lady beetles may not be destructive pests, but they can be a major nuisance. They don’t lay eggs inside homes—every beetle you see has found its way in on its own. When spring arrives, they emerge in large numbers from baseboards, attics, and walls, often clustering along windows in an attempt to escape. However, not all of them make it to the outdoors. It’s common to find piles of dead Asian lady beetles on floors or near windows.
3.
Staining and allergies
Asian lady beetles release a yellow, foul-smelling fluid when disturbed. This secretion can leave stubborn yellow stains on surfaces. In some cases this secretion can trigger allergic reactions in humans, causing symptoms like itchy or runny nose, itchy eyes, shortness of breath, wheezing, skin irritation, and sneezing.
4.
Challenge to Fruit Farms
Asian lady beetles aren’t considered a major pest because of how much fruit they consume, but rather because of the sheer number of crops they infest. They pose a significant threat to fruit destined for processing - especially for wine, jam, and juice production. Asian lady beetles tend to swarm in large numbers, clinging to grape clusters. This becomes a serious issue during wine production, as they can be unintentionally crushed along with the grapes. When crushed, they release a chemical that imparts a moldy, earthy flavour that can taint the flavour of wine, jam, juices, etc.
Fun Fact!
In Ontario the recommended threshold for grapes is 200–400 Asian lady beetles per tonne of fruit to prevent contamination.
How to get rid of Asian Lady Beetles?
If you have noticed Asian lady beetle activity inside or around your home, it is time to call in the pest control experts! Rural Routes Pest Control can provide control for the Asian lady beetle activity you are experiencing.
for more information about our Asian lady beetle control services.