Introduction
Ladybugs, also called lady beetles or lady
birds, are among our most beneficial insects.
They are voracious and efficient predators of
insect pests, and feed on more than 50 species
of aphids. A single ladybug will consume
thousands of pest insects in its lifetime, helping
to protect home gardens as well as valuable
commercial orchards and vegetable crops.
They don’t sting, transmit disease or infest food
supplies, and of the more than 450 species of
ladybugs in North America, only three feed on
plants.
Yet one species, the multicoloured Asian lady
beetle (Harmonia axyridis), has increasingly
become a cause of complaints. That’s because they
gather in large numbers in the fall, looking for a
safe place to overwinter. Attracted to homes and
buildings with sunny exposures, they will cluster on
outside walls and, eventually, work their way
indoors through cracks and openings. Their sheer
numbers can make them a serious nuisance for
some homeowners.
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Description
With their characteristic dome shape, orange-red
bodies and black spots, ladybugs are among our most
familiar insects. The main physical difference
between the various species in Canada is the
number of black spots on their wing covers, e.g.,
the two-spotted and thirteen-spotted lady beetles.
Multicoloured Asian lady beetles became
established in North America after their
introduction from eastern Asia in the 1970s to
control aphids and other crop-eating insects. Their
vigorous reproductive cycle and ability to
withstand fairly harsh winters has helped them
become a predominant species in Canada. They
are slightly larger than native species, typically 6 to
10 mm long, and range in colour from a mustard
yellow to a dark, reddish orange. They have a
varying number of black spots on their wing
covers, though some may have no spots. Also, the
multicoloured Asian lady beetle has two white oval
markings on either side of its head, and usually has
an M-shaped marking just behind its head. As with
many other insects, their bold colours are a
defence, warning birds and other predators that
they won't make a tasty meal.
Life Cycle
Throughout the summer, ladybugs feed on softbodied
insects, such as aphids and mealybugs. As
fall nears and temperatures drop, most ladybug
species prepare to overwinter on the forest floor,
often at the base of trees, under bark, leaves or
other debris.
The multicoloured Asian lady beetle,
however, is attracted to sunny areas, including homes
and buildings where they will congregate in the
hundreds, even thousands, seeking warmth and a
sheltered place to overwinter. Homes near fields
or forested areas are particularly susceptible.
After clustering on outside walls, many will work
their way into the dwelling through gaps in
doorframes and windowframes, eaves, utility
openings, foundations and wall siding. Once inside,
they become confused and gather on the walls,
ceilings and around windows looking for an exit.
Most of these stragglers die within a short time,
but others may find a safe spot to hibernate in the
attic or wall voids, emerging from time to time
during mild weather.
A larger invasion can be
expected for several days
in the late winter or early
spring, when they leave
their winter hiding spots
and try to move outdoors
to mate. The
multicoloured Asian lady beetle produces several
generations each year: the adult females lay
clusters of 10 to 50 tiny, light yellow eggs near
aphid colonies. The larvae are spiny and mostly
black with orange stripes, resembling tiny
alligators, and these larvae share the adult's
insatiable appetite for aphids.
Control of Multicoloured
Asian Lady Beetles
Once multicoloured Asian lady beetles have
moved in, there are few treatment options. The
best method is to simply sweep or vacuum them
up, then seal and discard the bag so they don’t
escape back into the home.
Preventing multicoloured Asian lady beetles from
entering buildings is the only method of control.
Exclusion techniques, including caulking and
weatherstripping, can keep them outdoors where
they belong.
Focus on the sunny, southwest sides of the home,
as shady areas are much less affected.
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Fix screens and caulk around windows and
door jams.
-
Seal any cracks and crevices in siding and the
foundation.
-
Plug holes in roofing, vents and attic walls.
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Inspect and seal gaps in service utility
entrances.
There are currently no pest control products
registered for the control of lady beetles.
Remember
Before Purchasing a
Pesticide Product
- Identify the pest correctly.
-
Use physical control methods
and alternatives to pesticides.
-
Read the label directions and safety precautions
before buying the product. The label must include
the name of the pest to be controlled and the
treatment location (e.g., indoor, outdoor, garden
uses, pet treatment).
-
Purchase only the quantity of product needed
for the treatment.
-
Alternatively, you may choose to hire a
licensed pest control operator.
When Using a Pesticide
- Carefully read all label instructions and
precautions before using pesticides.
-
Do not drink, eat or smoke while applying
pesticides.
-
Persons and pets should vacate the area during
treatment. Cover or remove aquaria.
-
If kitchen area is to be treated, cover or
remove food, dishes and utensils.
After Handling a Pesticide
- Always wash your hands thoroughly after
handling any pesticide product.
-
Do not permit persons or pets to contact
treated surfaces until residue has dried completely.
-
Provide adequate ventilation of treated areas
after use.
-
Wipe clean all surfaces that come in direct
contact with food, such as counters, tables and
stovetops, including indoor and outdoor surfaces.
-
Always store pesticides out of reach of children
and pets and away from food and beverages.
In Case of Accidental Poisoning
- Call a poison control centre immediately and
seek medical attention.
-
Take the pesticide container or label with you
to the emergency facility or physician.
-
Follow the first aid statements on
the label.
-
In case of accidental poisoning
of pets, seek veterinary attention
immediately.
When Disposing of Pesticides
Do not reuse empty pesticide containers. Wrap
and dispose of in household garbage.
Unused or partially used pesticide products should
be disposed of at provincially or municipally
designated household hazardous waste disposal
sites.
Use Common Sense
- These are general recommendations.
-
Consult the label for specific instructions.
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When in doubt, contact a professional.
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