Written By Jessica Alba.
Posted on January 2nd, 2020.
Most of us learned growing up that ladybugs are “good bugs” but is that still true?
I remember watching my grandmother tend to her garden one spring day a few years ago. My grandma is very particular about what she allows past her garden fence (most things don’t make the cut), and that day I learned she didn’t like ladybugs. She told me she even squishes them when she sees them.
“What?” I remember asking her. “Grandma, no- ladybugs are good bugs! They eat the other bugs that would eat your plants. You shouldn’t squish them.”
“I didn’t think these ones here are good.” She responded in her thick accent. “In Italy, yes, they are good. But not here.”
I assumed she was simply confused because of course ladybugs in New York are good, too, right? I thought it was common knowledge that they ate garden pests and thus keep crops healthy. But after taking a closer look at these small red beetles I realized that maybe my grandma wasn’t as wrong as I initially thought she was. Lady bugs are good in Italy, she was right about that- they’re even considered symbols of good luck over there- but not all ladybugs are the same.
North America has several different kinds of native ladybugs, but unfortunately, those beetles are probably not the ones most of us are familiar with. An invasive cousin of our native beetles, called the Asian lady beetle, has a population in the US that has been growing since it was introduced in the early 1900’s as a way for farmers to combat pests on their crops (read more about how to stop the spread of invasive species here). To be fair, the Asian lady beetle does eat the same menu of garden pests as our native ladybugs, but that doesn’t mean they provide all the same ecological benefits.
Native ladybugs, like the nine-spotted ladybug, are eaten by native birds and insects, meaning they play an important role in local food chains. Asian lady beetles are capable of biting when threatened and they can “skunk” attackers with a yellowish, foul smelling odor, which means they’re often over looked as a food source. Competition over the same food combined with a lack of predators means that native ladybugs are losing out to invasive ones.
A North American native ladybug. Photo source: Pixnio
A growing invasive population means that odds are when you see a ladybug it’s really an Asian lady beetle. This is particularly true if you see them indoors during winter. As the weather gets colder the beetles will move inside to find warmth, and although I can’t fault them for that, there’s no denying that some lady beetle infestations can become quite large and overwhelming, and may even require professional help to remove them all. Even as I sit here in my office writing this I can see lady beetles buzzing around my window and lights. It’s worth noting that our native ladybugs stay outside all year long, making them much less of a nuisance.
So how do you know if you’re looking at a native ladybug or an Asian lady beetle? To me, the most obvious difference is the markings towards the heads of the bugs: a black letter “M” on a white background will always be the Asian lady beetle. Our native species will have various head markings but never will they have an “M.” To learn how to identify other invasive insects, check out these activities.
An Asian lady beetle – note the tiny black “M” by the head. Photo source: Pixnio
As for what to do about the Asian lady beetle should you see them in your home or garden, well that’s up to you. While they do provide some benefits, like eating aphids, their presence means you’re less likely to see native ladybugs due to competition between the two. If they become a problem in your home, it’s best to get rid them and try to seal off any cracks and other entry ways you think they may have used to get in. To attract native ladybugs to your property, keep your garden healthy by supporting local pollinators.
Have you ever seen native ladybugs in your garden? Let us know in the comments below!