by Connie Oswald Stofko
I didn’t see many brown marmorated stinkbugs in October, which is the time when they are usually trying to get into our houses. Other Western New York gardeners have told me they have seen fewer–or even none–this fall.
Could the population of brown marmorated stinkbugs be declining in Western New York?
“It does seem to be that way,” said Liam Somers, state entomologist with the New York State Department of Environmental Conservation.
Brown marmorated stinkbugs in WNY
The brown marmorated stinkbug is an invasive species that arrived in Western New York in 2010. It’s called a stinkbug because when you step on it, it smells.
Because they feed on a wide variety of plants, the main concern has been damage to agriculture.
2018 seemed to be the peak population of these stinkbugs in Western New York, with sightings decreasing every year after that. That’s my take from what I have seen, what other gardeners have told me and what other local gardeners have said in comments on previous articles.
While we have anecdotal evidence, Somers said, we don’t have numbers on how many brown marmorated stinkbugs are actually here or whether the population has declined. The state Department of Agriculture and Markets was tracking them, but now that they are so widespread and have caused less damage, the tracking has ended, Somers said.
“It’s all good news,” he said.
Somers, who lives in Albany, hasn’t seen as many brown marmorated stinkbugs in his area, either.
“Personally, my house used to get invaded every fall,” he said, “and I had to vacuum them up. But I’ve seen a decrease.”
There are a few reasons why this decline might be happening.
Native fly targets stinkbugs
“It seems to have moved to the brown marmorated stinkbug,” Somers said.
The fly lays its eggs on a stinkbug, then the larvae burrow from the eggs directly into the stinkbug’s body. Only one larva survives within the stinkbug. After that larva emerges from the bug, the bug soon dies. See the life cycle of the Trichopoda pennipes here.
In addition, the US Department of Agriculture is testing the samurai wasp (Trissolcus japonicus) as a control for the brown marmorated stinkbug, he said. Trissolcus japonicus is the bug’s natural enemy in Asia.
“Temperature seems to be the biggest control” for the brown marmorated stinkbug, Somers said. “They don’t tolerate temperatures over 70 degrees Fahrenheit well.”
The heat doesn’t kill the brown marmorated stinkbugs, but it seems to reduce mating. They breed in the middle of summer, which is when Western New York saw record-setting high temperatures this year.
Local animals eat them
“More animals are feeding on them now than before,” Somers said. “It happens sometimes with a non-native species. It just takes time for (local predators) to adapt.”
The Chinese mantis isn’t a native insect, but it’s widespread here and eating brown marmorated stinkbugs. Birds and spiders are adjusting, too.
Are you seeing the same number of brown marmorated stinkbugs in your area of Western New York as you saw before? Leave a comment and please tell us what town you live in.