The fall season has finally arrived now that the overnight temperatures have dropped, signaling leaves to deepen in rusty reds and buttercup yellows, and awakening the local deer population’s pheromones, throwing them into full rut mode.
The bucks can be seen in fields sparring and attempting to spark with the does. Around the neighborhoods, pumpkins and straw scarecrows festoon doorways in celebration of the festive holiday season.
But, come one sunny afternoon, another sign of fall arrives as many front porches are suddenly aswarm with hundreds of ladybugs flitting about mindlessly, and all trying to get inside your house. Starting in October and on through April, they show up, especially on warm sunny days. Once ladybugs penetrate the home, they tend to mass on the ceilings and crawl around the windows seeking places to hibernate over winter. They typically return year after year, knowing they’ve got a good site to rest. Pheromones released by past ladybugs are detected by future generations. Also, the color of a home and the location are important factors. They tend to choose light colored homes that are nestled in forest or wooded areas. Homeowners have reported sinus problems due to these infestations.
But, these beetles are not native ladybugs – they are Asian Lady Beetles, officially called the Multicolored Asian Lady Beetle (Harmonia Axyridis), and they bite – worse, they stink. Today, these beetles have become a statewide pest. Fortunately, ladybugs are not structure-damaging insects. They will not eat home materials and will not lay eggs inside the home. Yet, if disturbed, the ladybug will stress, releasing a yellow, smelly substance from their joints. It is a defensive mechanism for the insect to defend itself from predators.
The Asian Lady Beetle was first introduced by the USDA in western parts of the U.S. early in the 19th century to control insect populations on fruit trees, and it has been a big help for farmers as a beneficial aphid predator and also in controlling other soft-bodied insects associated with trees, shrubs, ornamental plants and agricultural crops, reducing the need for pesticides.
Though releases are no longer taking place, the beetle’s recent population increase in Louisiana, Pennsylvania, and other northern states may not have resulted from those earlier USDA releases. Instead, they are thought to be from a new source that was accidentally introduced in New Orleans from an Asian freighter.
All ladybugs feed on aphids, scale insects, and mites. The most common native ladybug in North America is the Convergent Ladybug, a familiar species known to be gentle. Not only are native and invasive ladybug species competing for the same food source, the Asian Lady Beetle is hardier, and stronger. It also has an arsenal of a parasitic fungus that kills other ladybug species, especially when native ladybugs find and feed off Asian Lady Beetle eggs and larvae.
Homeowners need to know the best and first defense preventative to keep them from entering the house is to caulk cracks and crevices around doors, windows and pipes that enter the house, and replace or repair damaged clap boards. After the beetles have gained access to the wall voids or attic areas, it is not advisable to use an insecticide to control them. Insecticidal treatment of the voids may kill thousands of beetles, but there is the likelihood that another household pest, carpet beetles, will begin to feed on the dead lady beetles and might subsequently attack woolens, stored dry goods or other animal products in the home.
If numerous lady beetles are entering the living areas of the home it is advisable to locate the places where the beetles gain access. Typically, beetles will emerge from cracks under or behind baseboards, around window and door trim, and around exhaust fans or lights in ceilings. Seal these openings with caulk or other suitable materials to prevent the beetles from crawling out. A temporary solution is to use tape to stop the beetles. A helpful hint to remember: the beetles are attracted to light and can see light entering through cracks in the walls or ceilings. Initially, concentrate on sealing cracks in the rooms where beetles are most prevalent.
Although aerosol-type pyrethrum foggers will kill beetles that have amassed on ceilings and walls in living areas, it will not prevent more beetles from emerging shortly after the room is aerated. For this reason use of these materials is not considered a good solution to long-term management of the problem. Spray insecticides, directed into the cracks and crevices where beetles emerge will not prevent them from emerging and is not a viable or recommended treatment.
Black (ultra-violet) light traps may provide relief from beetles flying or crawling around the interior of homes. DO NOT use the type of light trap that utilizes an electrical grid (commonly called ‘bug zappers’) to kill the beetles inside the home.
Finally, the use of a vacuum is still the most efficient method of collecting and ridding your home of beetles. The major complaint for this method is that the beetles become agitated and expel the yellow, foul-smelling repellent, which is then circulated into the air by the vacuum exhaust. Also, it is advisable to empty the bag and beetles after each vacuuming.
A few words must be said in the Asian lady beetles’ defense. They do not kill trees, like, say, the invasive hemlock woolly adelgid. They do not spread disease or raise their young in attics. They do not yet seem to be bullies, rearranging natural ecosystems to suit themselves. They eat the aphids that plague pecan trees, soybeans and corn. But, given their rancid smell – like rotting peanuts or oranges – nothing much feeds on them.
Like most alien species’ introductions, there are up sides and down sides, but as far as the Asian Lady Beetle is concerned, it appears they are here to stay. To make the best of the situation, we need to be prepared and add bug-vacuuming to our winter-preparation chores.