Cones on our hemlocks - a source of food for birds
Lots of non-native insects have become invasive and have caused lots of problems. 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 some hemlocks, but so far, we've been lucky. At least there appears to be a cure for that problem at least on the scale of the home landscape.
Below are some of the non-native invasive insects we've found in our yard.
John hand picking beetles (the night before our first child was born)
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 turfgrass.
Regardless of the size of the population, they usually arrived in our yard right around the Fourth of July. Starting in 2010, however, they've been arriving earlier—more than a week earlier. Not a good trend. In 2015, for example, we saw our first one on June 25, more than a week earlier than in the past.
We find it easiest to just go around with a jar of soapy water and knock them off into the jar. 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 our yard, they like glade mallow, our native roses, Canada burnet, leadplant, and raspberries.
Summer 2010 was an especially bad year, 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, although even then, we still went around each day, collecting beetles in soapy water.
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, but in 2010, the beetle's population seemed to decline and our American cranberrybush recovered, much to our surprise.
Our blackhaw viburnum is surviving
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? I'll stick with my blackhaw, raggedy though it may be. At least it supports life!
I suspect we'll never be rid of this beetle, but perhaps its population has stablized somewhat.
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, but is expanding its range (perhaps due to climate change?) to other parts of the US.
These sawflies (technically not caterpillars) 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 wasn't going to happen soon enough to save the glade mallow or rose mallow (hibiscus).
Hibiscus leaf, shredded by sawflies
We found a very simple, safe solution: a very dilute solution of Dr. Bronner's Peppermint liquid soap! We used about a one to ten concentration and just sprayed the sawflies. It seemed to work almost instantly, though I had to keep at it for two or three days as new sawflies appeared. It saved the plants and didn't involve toxic chemicals.
IMPORTANT NOTE: Be sure it's the sawfly you're dealing with! This plant is also a host plant for the great hairstreak butterfly (not in our area). In this case, a few nibbles out of the leaves is cause for celebration! The plant can easily withstand this.
Lily leaf 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 look-alike non-native.)
It has a particularly gross larval stage, covering itself with its "fecal shield." Yes, it coats itself with its own poop—admittedly effective.
The 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, since I have many more native bees than honey bees.
Honey bee swarm—solid cone of bees
A few years ago, our neighbor described hearing a sound like a power saw, looked up, and saw (literally) tens of thousands of honey bees landing on his Japanese maple tree. We found a beekeeper to take them away the next day, so they should now be in a new home making honey.
This is good news for the useful honey bees, but we can only imagine how many nectar resources they use, leaving less for our native pollinators.
Cabbage white butterfly
Cabbage white butterfly
This cabbage white butterfly is native to Europe and was brought to this country in the 1860s. We have them flying all around the yard.
Apparently, they've impacted the population of a native white butterfly, and they're certainly a problem in our vegetable garden.