Q: What should I do about Asian beetles? There are hundreds of them on my house.
Multicolored Asian lady beetles (Harmonia axyridis) vary in color and the number of spots. Photo: Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org
A:  There are multiple species of insects in our area that are native to Asia. The ones on your house are Multicolored Asian Lady Beetles (ladybugs). These beneficial insects are looking for a sheltered place to spend the winter. For this insect, or any other insect trying to enter on chilly nights, all you need to do is seal any gaps, cracks, or other access points. There is no effective repellent, and while the insects won’t harm people or damage the home itself, they can be a nuisance when they find their way in, since they are trying to find shelter for the winter. Check the window screening for tears that need to be repaired, and the door weather stripping for any gaps or worn-out pieces that require replacement.
By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.
Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.
Q:Â Why are several perennials in my garden bed turning black? Can they all be affected by the same disease?
A:Â Most plant diseases are not that wide-ranging, but in this case, the black residue is not an infection. It is a fungal species, but this fungus does not cause plant disease, as it only grows on the surface. Named for its black color, sooty mold is a group of fungi that feeds on the sugars in honeydew. Honeydew is a waste secretion produced by sap-sucking insects, such as aphids, leafhoppers, soft scales, and planthoppers (which includes Spotted Lanternfly).
The numerous questions that UMD Extension receives each year about sooty mold often result from the presence of Crapemyrtle Bark Scale and Spotted Lanternfly. At this time of year, a heavy buildup of sooty mold from high populations of high-bark scale or lanternflies can be a prominent eyesore. Reduced rainfall that isn’t diluting or rinsing away the honeydew contributes to the problem, but it’s also due to increased insect feeding. (The juvenile lanternflies present earlier in the year don’t generate as much honeydew.)
Sooty mold wears off on its own over time. If the insects generating the honeydew are suppressed (which is not always necessary from a plant health standpoint), it deprives the sooty mold of its food source. If you want to try removing the residue, look for products with a horticultural oil active ingredient, which include specific directions for sooty mold treatment on the label. The spray may make the mold easier to dislodge several days later using a strong spray of plain water from a garden hose.
By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.
Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.
Soldier beetle on the bloom of a golden aster. Photo:Â Miri Talabac
Q:There are many insects visiting my pollinator garden that look like yellow-orange versions of a firefly. Some of the petals are missing on those flowers. How do I keep them from chewing my plants?
A: These beetles are innocent bystanders and are not the cause of damage, even though that’s where you see them most. These are soldier beetles, and although beetles have chewing mouthparts, soldier beetles are primarily pollinators as adults and predators as larvae.
The pollen and nectar in the blooms of plants in the aster, carrot, and milkweed families are favored, and where you’ll often find them, dining solo or mating. Adults can also eat soft-bodied insects, which include aphids and caterpillars.
Occasionally, you may find a soldier beetle clinging to a flower head by its jaws and dangling with wings spread, dead. This is a work of an entomopathogenic (insect-infecting) fungus, an example of how natural factors impact insect populations, both for species we consider pests and those we consider beneficial.
Soldier beetle larvae hatch from eggs laid in the soil and feed on the eggs and larvae of other insects they encounter. Their prey can include grasshoppers and caterpillars, and these garden helpers are great for suppressing pests like cutworms, corn earworms, and cucumber beetles. The larvae overwinter underground. To provide hunting grounds and shelter from the weather, do not remove the protective blanket of leaf litter and avoid tilling the soil.
Velvety soldier beetle larvae eat many ground and plant-dwelling pests.
If flower petals go missing, another culprit is to blame – probably a chewing insect like Japanese Beetles or Asiatic Garden Beetles, but in some cases, a slug or snail. (Deer and rabbits tend to eat the entire flower head, so their damage tends to be more extensive than just nibbling around the edges.)
Missing its petals doesn’t necessarily ruin a flower’s wildlife value. Tolerate the damage if you can, or find a chemical-free way to discourage feeding. For example, flowers grown for cutting (like dahlias or mums) could be enclosed individually in small mesh bags before they open fully to exclude pests. However, that would deny pollinators access, too.
By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.
Have a plant or insect question? The University of Maryland Extension has answers! Send your questions and photos to Ask Extension. Our horticulturists are available to answer your questions online, year-round.
