'T'Wasn't Me!

Tuesday, October 15, 2024

‘T’Wasn’t Me!

Today’s special animal friend is the Brown Marmorated Stink Bug, Halyomorpha halys.  This invasive insect pest, native to Asia, is pestilentially invasive in 38 states and the District of Columbia, according to the EPA.  It was first collected in the U.S. in 1998 in Allentown, PA.  It has also invaded (former Soviet) Georgia, Turkey, Europe, and South America.

There are about 4,700 species of stink bugs and shield bugs in the Pentatomidae family.  They have piercing, sucking mouth parts with which they pierce and suck the leaves, stems, and fruit of plants, causing significant damage to many crops around the world.  The brown marmorated – “marble-patterned” – stink bug is a year-round pest in American fruit orchards and has badly damaged the hazelnut crop in Turkey, among other depredations.

As you can see, they’re small and brown, kind of cute if you don’t dislike insects in general.  Some people say they bite.  As a defense against predatory birds and lizards, they have glands on their thorax that emit trans-2-decenal and trans-2-octenal, producing a scent that is “pungent, like coriander,” one reads.  We have them here, and I have not noticed a smell.  Maybe they didn’t think I was a threat.   

Stink bug mating – you knew this was coming – involves males’ releasing pheromones and low frequency vibrations.  Females also vibrate, and a couple comes together when the vibrations feel right. I can’t find a good description of mating, but it looks like this:

Females lay eggs in clusters of 28 on the underside of leaves.  They hatch into nymphs which go through five instars or growth stages, in which they shed their exoskeletons and grow into a larger one.  In optimal conditions – such as those found in much of the United States – a new stink bug can reach adulthood in 35 days.  They can go through as many as six generations in a year.  Each female can produce 400 eggs during her lifetime.  If you think about the exponents here, it’s understandable that they have proliferated madly across the country, leaving the USDA in a complete fuddle.

Some insecticides are effective, and more are being tested and may eventually be approved for use.  Pheromone-baited traps can be useful for localized infestations.  The invasive Joro spider is a predator of brown marmorated stink bugs, but it has its own issues as an invasive species.  Birds and wasps eat some of them.  I would, after a modest amount of research, conclude that they are currently a really big problem, but there’s a chance that we may be able to slow the spread if a really effective insecticide is approved soon.  There’s a lot of bureaucracy involved in this.