Ohio's official State Insect is the Seven-Spotted Ladybug - Coccinella septempunctata - and they perform a very important agricultural task: aphid control.  Unfortunately, this is not the species of Ladybug that most "know" best.

The "pest" Ladybug that many Ohioans know all-too-well is the Multicolored Asian Lady Beetle - Harmonia axyridis.  This species was introduced into the United States by the U.S. Department of Agriculture as a biological control agent for aphids and scale insects.  It has been found overwintering in Ohio since 1993, becoming a yearly pest for many Ohioans.  All "pest" information that follows is specific to this September-through-April visitor.

• Ladybugs are usually about 1/4" in length and round in shape.  Their heads are marked black and white, and their Elytra (forewing) colors vary widely between yellow, tan or red with black spots, or even black with red spots.  Some red or tan varieties have no spots at all.


• Asian lady beetle larvae are usually black with orange markings, elongated, flattened, and covered with small spines.  The oval and yellow eggs are laid upright in clusters of about twenty.  The life cycle from egg to adult takes about three-to-four weeks depending on food availability and temperature, and there are multiple generations per year.  Adults can live for more than one year.


• Ladybugs are predators of aphids and other scale insects.  In addition to agricultural fields, they can be found on a wide variety of outdoor plants and garden crops.


• Beginning on warm sunny days after the first chilly nights of mid-to-late September and early October, large numbers of these ladybugs can be found on the sun-warmed south and west sides of light-colored homes and other buildings.  In their native Japan, they flock to south and south-west facing cliffs and rock outcroppings, crawling into cracks and crevices to overwinter.  Here in Ohio, they will enter any opening they can find around windows, doors, siding, chimneys, and utility outlets, then remain there for the full Winter.  They can be an immediate pest, but also during warm Winter days, some insects wake up and continue their pest behavior.  It is not uncommon for thousands of these beetles to congregate in attics, ceilings and wall voids.  Due to the warmth of the walls, they will move around inside these voids and enter the living areas of the home.


• Ladybugs do not eat wood, building materials or human food.  They also do not bear any diseases, but they can still be direct pests to people.  Ladybugs can bite, which can cause irritation and stinging for many people.  They also secrete a yellow defensive chemical that smells quite foul and can lightly stain walls and other surfaces.  If this chemical is secreted, more beetles will "come to the rescue."  Some people report contact dermatitis in reaction to these secretions.  Although it is not as common as dermatitis, some also report sinus irritation.  Immediate hand/skin washing is recommended for those who are highly sensitive or allergic.  In at least one study, sinus and skin irritations began to decrease immediately following the removal of ladybugs from homes.


• Ladybugs should never be crushed inside the home.  In addition to the foul smell, beetle forewings have long been used for color dyes.  Similar to compounds from crushed Cochlear beetle forewings, used for years in red softdrinks which Boy Scouts and Girl Scouts nicknamed "bug juice," ladybug forewings contain compounds that will cause stains, particularly on porous surfaces such as painted walls and wood.  These stains can be permanent, and in some cases have even been known to lightly "bleed through" new paint applied over top of the stains.


• After the ladybugs have taken up winter residence, insecticidal treatment in voids may kill thousands of beetles; however, the dead ladybug carcasses will present a major food source for other household pests such as carpet beetles, which - upon population explosion followed by "running out" of dead ladybugs - may subsequently attack woolens, stored dry goods, or other animal products in the home.  Beetle light traps may be purchased from most pest professionals.  Do not use electrified traps ("bug zappers") for beetles inside the home.


• Treatment of the outside west- and south-facing walls can offer some relief from infestations where the task of completely sealing the exterior is difficult or impossible, and should be completed in August or early-September.