Ladybug, ladybug, fly away home. Your house is on fire, your children all gone.
This ancient nursery rhyme, made famous with slight variation by Peter, Paul, and Mary, apparently had its roots in medieval times when hops were set on fire in the autumn after the harvest to clear the fields. The burning of crops also had the benefit of reducing the numbers of pests finding winter-refuge in the rubble. Unfortunately, the collateral damage was the death of ladybug larvae and pupae that remained behind as the adult beetles escaped the flames. The rhyme certainly presents an interesting allegory of one of our favorite beneficial insects – ladybugs, also called lady beetles and lady bird beetles.
Lady beetle larvae look like small alligators and are very active as they hunt prey.
With the return of bright and sunny afternoons this week, my house was pelted with ladybugs suffering from the delusion that my home was their home. This petite invasion is underway not just in my yard, but throughout our area as the Asian multicolored lady beetle, a.k.a. the Halloween lady beetle, seeks winter refuge in houses, schools, and office buildings. Harmonia axyridis is a prodigious killer of aphids and other nasty pests in our gardens. In one grove of barberries, I witnessed the annihilation of a booming aphid population. The dazzling ladybug adults and their alligator-like spawn so completely attacked their prey that I could not find a single living aphid a couple of weeks after they discovered the aphid patch. Harmonia adults have been reported to consume more than 250 aphids each day, and the larvae may eat more than 1,200 during their development. In addition to eating large numbers of aphids, they devour other pests including adelgids, scales insects, and psyllids. Like many predators, they also eat each other.
As early as 1916, deliberate attempts were made to introduce Harmonia axyridis into the United States from their aboriginal home in Asia. We are not exactly sure how or when this ladybug arrived, but by the mid-1980s, it was firmly entrenched in the southern United States. By 1993, it was reported in several Mid-Atlantic States, including Maryland. It is now distributed from Florida to Washington State. I have heard reports of people being “bitten” by ladybugs and confess that I have gotten a small nip every now and then. The “bite” was something less than that of a Doberman and more like a tickle. No break in the skin is “no foul” in my book. When ladybugs are handled or disturbed, they can release a smelly, bitter, secretion that may leave a faint yellow stain on your skin, wall, or curtain. This neat trick is called reflex bleeding and it is their way of delivering a nasty surprise to a would-be predator.
Why the fascination with invading our homes? Are these ladybugs simply nosey or are we next on the menu now that all the aphids are gone? As winter approaches, Harmonia seek protected locations such as crevices and cracks in rocky cliffs and outcroppings. After aggregating by the thousands, they find protected locations within which to spend the winter. Throughout the cities and suburbs of Washington and Baltimore rocky cliffs are scarce, but homes and buildings are plentiful. Now is the time that Harmonia fly to our homes and places of work and attempt to find refuge.
Small, lemon-yellow eggs on leaves are stems are likely to be eggs of ladybugs.
Any cracks around windows, breaks in stone foundations, unscreened vents in the attic, or gaps in facer boards can allow entry to your home. Once inside these ladies settle in for the winter, but on warm days in the late winter and early spring they may become active and find their way to sunny windows where they attempt to escape. To prevent these ladies from entering your home, repair screens on your windows and vents, caulk your foundation, and eliminate points of entry to your home. If you find the beetles a problem indoors, carefully sweep or vacuum them up and release them in a protected spot outdoors such as a tool shed. Traps can be purchased and used indoors to catch these ladies alive. The misguided insects can then be placed outside. One of the real delights of the season is to visit the rocky crags of Old Rag Mountain in Virginia or Sugarloaf Mountain in Maryland to witness thousands of multicolored Asian ladybeetles gathering on the sunny cliffs for one last bask in the sun before turning in for the winter. You better hurry. The arrival of the multicolored Asian lady beetle is a sure sign that Old Man Winter is just around the corner.
References
For more information on the multicolored Asian lady beetle and ladybugs in general, please visit the following web sites:
http://www.nysaes.cornell.edu/ent/biocontrol/predators/harmonia.html
http://ohioline.osu.edu/hse-fact/1030.html
http://www.geocities.com/sseagraves/ladybuglore.htm