Harmonia axyridis, The Asian-Spotted Ladybird Beetle
I found this weird little creature stuck to a leaf on a rose bush by the picket fence in front of the San Juan County Land Bank office on Monday, June 24, 2019 when I walked down Argyle and rounded the corner onto Caines (does anyone on the island actually use street names? Where the heck is Caines, right?)
Brought it home because I couldn’t resist the mystery of figuring out what it might be. What on earth are those spiny things at the end? Is it some sort of pest insect?
After taking a few photos, I did what drives my husband crazy sometimes. I left the leaf with this little spiny-ended thing on the table, in a cup, without a lid. Yep. Just like when I left the really fat deer tick I had on my desk. The one that laid eggs…that hatched when I wasn’t paying attention. This is when it’s really handy to have sticky tape nearby, otherwise you have to vacuum every 10 minutes for about a month to finally sleep at night without feeling like things are crawling all over you and burrowing into your skin. This link should take you to my facebook page post about “Big Bertha.” https://www.facebook.com/buggingyoufromSJI/posts/2375866245969416
This morning, after my cat got me up with incessant meowing right in my ear, I sat down at the table with a cup of coffee. Millhouse (the cat) isn’t supposed to be on the table, but when my husband isn’t around, anything goes! He was staring something down that was m.o.v.i.n.g! Fortunately, I reacted faster than he did. I tipped over the little medicine cup I’d put the leaf in to thwart this little creature’s attempt at a fast getaway.
Carefully sliding a piece of paper under the cup, I could see it looked like a ladybug. Ladybugs come in different colors, with different spots, and there are quite a few species one could encounter on San Juan Island. This beetle goes by an assortment of names. It’s often referred to as the Multi-colored Asian Lady Beetle or sometimes the Halloween Beetle because in some places they show up in large numbers at Halloween! 🎃😱
This beetle’s scientific name is Harmonia axyridis (The Asian-spotted Ladybird Beetle). It was imported to the United States as early as 1916 to help control pests as a biocontrol agent. While “Miss Harmonia” eats aphids, thrips, and scale insects (and manages these pests fantastically in soybean crops), she isn’t native and these pest insects aren’t all she eats. Asian-spotted Ladybird Beetles also eat native coccinellid beetles (native lady bugs) and even butterfly eggs. In the winter, she can bring her friends and invade your home. When handled, the ladybird beetles can excrete a stinky defensive chemical from their leg joints. This makes removal of large numbers of them from inside homes somewhat problematic. You don’t want to have them discharging this awful odor that will linger….all…winter!
Another unfortunate consequence of importing these beetles is their love of wine grapes. 🍇 🍷 Asian-spotted ladybirds will eat grapes and then the grapes end up contaminated with an awful smell lingering on them. While I personally don’t drink wine, I know lots of people do and they’d be very unhappy if it tasted like essence of ladybug…a twist on a new aromatic bitter perhaps!
Did I squish her? Nope. I put her in the tree near our bird feeder. It’s possible she will become part of the food chain. While not all birds eat these beetles, some do. Insects and arachnids like robber flies, dragonflies, ants, various ground beetles, and cellar spiders also eat them.
If you see them, should you squish them? That’s up to you and how confident you are that you’ve identified it correctly. I wouldn’t want to mistake a helpful native ladybug as an invader. I recommend that instead of buying ladybird beetles at the garden store to release in your garden you establish native habitat to attract and support native species of ladybugs.
As I looked a bit more into the literature about Harmonia axyridis, I was intrigued with the publication of some research about the biochemistry of the liquid they secrete. It has been found to have strong antimicrobial action against strains of bacteria that are pathogenic to humans. This fluid has even been examined for its action against malaria. Perhaps these beetles don’t belong in the garden, but in your medicine cabinet instead.
References and further reading