Non-native insects

Non-native insects have been attacking many native plants in our region (and in many other areas).

Currently, the emerald ash borer is a huge problem, but it’s only one of many that will be disastrous for our whole region. (I’m saying “will” — not “could” — since it appears that some problems are inevitable at this point.) Fortunately, we don’t have an ash tree.

We do, however, have a few hemlocks. So far we’ve been lucky and haven’t seen the hemlock wooly adelgid.

There appears to be a cure for that problem, but only on the scale of the home landscape, not in forests, since it involves treating individual trees.

Hemlocks in danger from adelgids

Below are some of the non-native invasive insects we have found in our yard.

Japanese beetles

Our population of Japanese beetles varies from year to year. I think if people had less lawn area, we might see a big decrease in the population, though, since their grubs live in the soil under turf grass.

Regardless of the size of the population, they usually arrive in our yard right around the Fourth of July.

Japanese beetle eating a native rose

UPDATE: After routinely emerging around July 4 every year, now in 2024, we have had Japanese beetles since JUNE 15!!! This is one of the many ways things are changing with the climate. Not a good thing!!!

Beetle traps?

Summer 2010 was an especially bad year for Japanese beetles (or, rather, a good year for the beetles, bad year for our plants …), so we decided to again try the Japanese beetle traps for the first time in many years.

Even though people say that they just attract beetles that wouldn’t otherwise be in your yard, we figured we had so many that summer we couldn’t be in any worse shape. We concluded that the traps seemed to be worth having when there’s an especially severe infestation. We haven’t used these traps since, though, and haven’t had a need to.

Trap plants

Collecting Japanese beetles

Instead, we just go around with a jar of soapy water and knock them off into the jar. (And as you can see from this vintage photo, we’ve been doing this a long time!) They’re lethargic in the early morning, so that’s the best time to get them.

It’s most efficient to look for them on their favorite plants — in other words, trap plants.

Primrose used as a trap plant

In our yard, they like biennial primrose and Canada burnet and the flowering raspberries.

At least in our yard, their favorite seems to be biennial primrose (Oenothera biennis), so much so that I’ve decided to grow a few more of these “trap plants” so I can “harvest” the beetles efficiently by just going to these plants.

Since I’m collecting them frequently, they don’t seem to harm the plants unduly.

Asian ladybug (Harmonia axyridis)

There are many types of Asian ladybugs, which have multiplied to the detriment of our native ladybugs. Why? Probably because they were sold as a biocontrol for aphids.

Asian ladybug
Asian ladybug
Seven-spotted ladybug

This is a seven-spotted Eurasian ladybug.

Cabbage white (Pieris rapae)  

Cabbage white

A widespread, abundant non-native import from Europe and was brought to this country in the 1860s. They’re all over our yard, creating a problem not just for our edible garden, but also competing with our own native white butterflies.

HOST PLANTS: members of the mustard family such as cabbage, broccoli, brussel sprouts

More info at Butterflies and Moths of North America

Hibiscus sawfly

Hibiscus sawfly

A new invader, the hibiscus/mallow sawfly (Atomacera decepta) appeared in our yard for the first time in 2011.

It’s actually native to the mid-Atlantic and Midwest states, so it’s not the typical Eurasian invading insect.

I have read that it’s expanding its range (perhaps due to climate change?) to other parts of the US.

These sawfly larvae are capable of completely defoliating the plant in a very short time. Usually we let things be and let an insect’s predator find this new source of food, but this didn’t seem like it would happen soon enough to save the plant.

Brown marmorated stink bug

IMPORTANT NOTE: There are also NATIVE stink bugs, which we do NOT kill. The BMSB has stripes on its antennae.

Brown marmorated stinkbug

The BMSB, as it’s “affectionately” called, is another new-ish pest. In 2014 or so, we sent samples of one we found in our yard to a university that was studying it. Now we (and I suspect everyone else) see them so frequently that I don’t think they’re still asking for samples.

Stinkbug larvae and empty eggshells

These may look like ladybugs, but they aren’t. They’re the BMSB larvae, having just hatched out of their eggs.

As an insect that isn’t native to our area, it’s not adapted to overwintering in our cold, snowy climate. So where does it go? Into our houses, of course! We don’t seem to have as large an infestation as other people, but they’re not appealing to find. We certainly don’t want to squash them, releasing their truly stinky odor, so we stick them in old glass spice bottles and put them in the freezer. When they’re dead we put them in the trash.

I haven’t noticed damage on our habitat plants, but we have found them in our edible garden. They have the potential to be a huge pest in agricultural areas, though, which is why scientists are studying them.

Lily leaf beetle

Lily leaf beetle

This is an Eurasian non-native beetle. We saw this first in 2015, covering what we had previously thought of as our native Turk’s cap lily. (We later realized that this plant is a non-native look-alike, which we have since removed.)

Lily beetle fecal shield

Besides damaging the plants, this beetle has a particularly gross larval stage, covering itself with its “fecal shield.”

Yes, it coats itself with its own poop — admittedly effective and disgusting to deal with.

Viburnum leaf beetle

After viburnum leaf beetle

Our viburnums — especially our arrowwood viburnums — were hard-hit by the invasive viburnum leaf beetle that arrived in the early 2000s.

Unfortunately, we had just planted $100 worth of these plants the year before the beetle arrived in our area.

And just as unfortunately, this native shrub turned out to be one of their favorites. Our arrowwoods were totally dead after two or three years.

Wouldn’t you know that the non-native viburnums were less affected. It makes sense, though, because the non-native shrubs probably have defenses against this non-native beetle whereas our native shrubs don’t.

Unfortunately, many “experts” recommend that people plant those non-native viburnums. What would be the point? For a while we had a blackhaw viburnum, ragged though it might have been. At least it supported life! It eventually outgrew its space, though, so we had to remove it. (Another victim of my tendency to plant what would become a large shrub too near the path …)

I suspect we’ll never be rid of this beetle, but perhaps its population has stabilized somewhat, especially as it has killed off so many of its host plants.

The honey bee

Honey bee

Commercial agriculture relies on honey bees to pollinate their acres of monocultures. But honey bees aren’t native to North America, and they may actually be harming our native bee populations by competing for ever-decreasing habitat resources.

They haven’t caused any problem that I’m aware of in my yard. I have many more native bees than honey bees and I have ample floral resources so I haven’t attempted to control them (as if I could), but I prefer to provide for native bees.

Resources

Reflections

The effects [of the emerald ash borer and the hemlock wooly adelgid] will go far beyond what you see on a hike or how you feel about the loss of a tree on your property. They will ripple through forest ecosystems, affecting other plants, animals and water supplies.
~ Maggie Koerth-Baker, After the Trees Disappear, New York Times 6/30/14 – an excellent (though depressing) article (If you aren’t a NYT subscriber you may have to google the article title)