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University
of Rhode Island GreenShare Factsheets
Asian
Lady Beetle Harmonia
axyridis
Coleoptera: Coccinellidae
The Asian lady
beetle, sometimes known as the Halloween lady beetle or the Japanese
lady beetle, is a yellow-orange ladybug that is often seen in large
congregations near the end of October. As many as several thousand
adult beetles have been found congregating outside on windows, doors,
porch decks, etc., often getting indoors as well and creating a
nuisance. The beetle is native to Japan. The Asian lady beetle does
not bite, sting, carry human diseases or feed on wood, clothing
or food; they also do not reproduce indoors. In spite of annoying
populations, these insects are considered beneficial to agriculture
and garden landscapes because they feed on harmful aphids and some
scale insects associated with trees, shrubs, bushes, low growing
ornamentals, roses, wheat, cotton, tobacco, pecans and other crops.
Adult Asian
lady beetles are oval, about 6 mm (1/4 inch) long, and range in
color from yellow to orange to red, with or without black spots
on the wing covers. The number of spots varies drastically,
ranging
from zero to at least twenty. The spots are sometimes reddish in
color. The head is usually concealed from above and the white
pronotum
(top covering of middle body part) generally has a black "M"-like
shape. The larvae are elongate, somewhat flattened and covered
with
minute spines. Eggs are yellow, oval shaped and laid upright in
clusters of about 20, usually on the undersides of leaves. Usually the
life cycle from egg to adult requires three to four weeks during
cool spring weather. Eggs hatch in three to five days. Larvae feed
on aphids, scale or other insects for 12 to 14 days. Pupation lasts
five to six days until adults emerge. The adult stage is the longest
with some beetles living up to two to three years. It is believed
that females overwinter unmated with the aggregate population of
both males and females mating later in the spring. Most beetles
are reported in October and November when congregating to find overwintering
sites, and again in February and March during bright, warm, sunny
days, as they attempt to return to their outdoor habitat. Adults
release a pheromone that attracts other lady beetles of the same
species; when one beetle lands, many others soon follow. This lady beetle,
a tree-dwelling species, was introduced from eastern Asia and released
by USDA as a biological control agent in many states between 1977
and 1981. These releases apparently did not result in establishment.
The beetle was first recovered in Abita Springs, Louisiana in 1988.
This population apparently entered the United States from an Asian
freighter docked in New Orleans. The beetle was found in Georgia
and Mississippi in 1990; it has since moved throughout the Northeast
and into some western states as well. The exotic Asian lady beetle
has had a positive impact in many states because of the beetle's
effectiveness in controlling aphids on pecan trees, pine trees,
ornamental shrubs, cotton, wheat, tobacco, roses, etc. Moreover,
nuisance populations may decrease with time; recent research conducted
in North Carolina indicates that as much as 25% of the Asian lady
beetle populations has been parasitized by a tachinid fly. Such
parasites are also found in Rhode Island, indicating that the lady
beetle population here may decline in the future as well. Prevent
Entry: Since lady beetles in late summer and autumn may move
to overwintering sites in houses, sheds and other buildings, it
is important to use a good quality silicone or silicone-latex caulk
to seal cracks around windows, doors, siding, utility pipes and
other openings. Replace and repair damaged door and window screens.
Install insect screening (5-mesh should be adequate) over attic
and exhaust vents to prevent beetle entry. Since beetles are attracted
to light, they are usually found around windows and lighting fixtures. Disposal:
Remove beetles from inside the home with a broom and dust pan
and/or vacuum cleaner. The beetles release a harmless but staining
orange substance when stressed; killing them with insecticides,
squashing them, or handling them may result in orange stains on
walls, floors and fabric. Collect the beetles from indoors and deposit
them outside under a bush or in some other covered area well away
from any homes. It is best not to kill these ladybugs--they may
return the favor by eating harmful aphids from your vegetable and
ornamental plants later in the season. Insecticides:
We do not recommend using insecticides against this beneficial insect.
Adapted
from the Ohio State University Extension, 1999
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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