Monday, January 25, 2016

Apple #725: Brown Marmorated Stink Bugs

I've had a request!  Daily Apple reader Millicent wants to know, in short, what's the deal with stinkbugs.  She said:

What is up with so-called stink bugs? I just moved one out of the house yesterday, not handling it directly but with a Bounty paper towel, and my hands still stunk afterwards. A friend and I were talking about them this weekend, and we both think that these bugs weren't around--certainly not in these numbers--even ten years ago.

I'm a little surprised that Millicent discovered one of these bugs in her house in January, because I'm willing to bet that, like ladybugs, they hunker down and sleep for the winter and emerge in spring.  I'm also willing to bet an enormous amount of money that these are a non-native species that arrived here recently and have no predators, and that's why they're suddenly everywhere.  Ten thousand dollars, that's what I'll bet.

I asked Millicent to send me a picture of the bug she saw because often the common name one person has for a bug is different than another person's common name, so I wanted to make sure I was going to talk about the bug she meant.

She sent me a link to a general Google search page for "stink bug," so I am 95% certain that the particular stink bug she saw is the Brown Marmorated Stink bug.

The stink bug in question -- Brown Marmorated, that is.
(Photo by Thomas V. Myers, National Pest Management Association, sourced from USA Today)

And it turns out, your Apple Lady is correct on all points.  I'll take that $10,000 now, please.

  • There are some 4,700 stink bug species in the world, and about 250 of them are native to the US and Canada.  We never paid much attention to any of them because they weren't here in hordes.  Then the Brown Marmorated stink bug (Halyomorpha halys) showed up.
  • The Brown Marmorateds are native to several countries in Asia -- China, Japan, Korea (North and South, presumably), and Taiwan. They made their first recorded appearance in the United States in Allentown, Pennsylvania in 1998.  It is presumed that they traveled here on some sort of shipping container.

Billy Joel should probably write another verse about the stinkbugs showing up in Allentown.

  • This species of stinkbug does have predators that are native to the US and Canada -- other types of stink bugs, assassin bugs (yes, there is such a thing), and parasites that feed on their eggs.  But these predators also prey on several other bug species, so there aren't enough of them to tackle the ever-expanding Brown Marmorated population.
  • They have now been sighted in at least 40 states, and in very high numbers in 19 of those 40.
  • They pretty much eat everything.  They like just about every kind of fruit that grows on a tree -- citrus fruits, apples, peaches, plums, mulberries, persimmons, figs, you name it they eat it -- plus sweet corn and field corn, ornamental trees, soybeans, lima beans -- pretty much every kind of bean --  green peppers, and weeds.
  • They will poke a straw-like appendage through the skin of the fruit and suck up the sap, leaving behind clusters of brownish white badness.  Some people say the damage they leave behind is often in the shape of a cat face, but I think those people are a little creative with their visualizations.

Damage to an apple caused by the pernicious Brown Marmorated stink bug.
(Photo from Penn State University Department of Entomology)

  • When the bugs are frightened or disturbed or squashed, they emit a very unpleasant stink from their glands.  It can be difficult to get the stink off your hands or your clothes. Some people are allergic to it.
  • They're otherwise harmless to people -- they don't sting or bite -- but they can be annoying as all get-out, especially because of the stink.  And they're hard to get rid of.
  • Most pesticides don't work on them, including the kinds of sprays that are sold to the general public for in-home use.  If you smash them as you would any other bug, you'll get the stink on your skin or your clothes or your carpet or your furniture. 
  • People suggest using a vacuum to suck them up, but if you get enough of them in your vacuum, they can stink up the vacuum.
  • One entomologist from Cornell University says a better way to kill these stink bugs is to fill a household spray bottle with a solution of soapy water, which is about 1% or 2% soap.  Dish soap is probably the easiest thing to use.  Spray 'em to death.
  • The best thing to do is to make sure the stink bugs don't get in your house in the first place.  Seal up cracks along window frames or around doors with caulk, use those shields you can stick on the bottom of your door, do as much as you can to stop up any crevices a stink bug could sneak through.
  • They'll most likely want to get into your house before winter comes so they have a place to sleep through the cold weather.  Then when things warm up in spring, they'll start stirring again.  That's when most people notice them out and about.  If you happen to catch them just after they've woken up, it won't take much to bump them off because they'll still be groggy and hungry and slow. 
  • The good news is, it looks like some birds here in the US are beginning to develop a taste for the Brown Marmorateds, and people have also reported seeing some lizards eating them too.  So maybe more natural predators will emerge and help us keep these stink bugs from eating every last thing in sight and stinking up the joint besides.

Normally, I include more pictures in an entry, but these bugs are not so attractive looking, and photos of their eggs or of them swarming give me the willies.  So I'll provide links for those who don't mind looking at such things and move on.

Penn State University, Department of Entomology, Brown Marmorated Stink Bug
Bill Cary, Indianapolis Star via USA TodayIt's stink bug season: Here's how to get rid of them, April 3, 2015
Doyle Rice, USA Today, Ding, dong, stink bugs calling on warm, cozy homes, October 15, 2013
New Jersey Agricultural Experiment Station, Rutgers, Brown Marmorated Stink Bug FAQs
Orkin, Stink Bugs 

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