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How to Tell a Male Stink Bug From a Female One

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Stink bugs live in most states, and they like to feed on fruits such as grapes, blackberries, peaches and apples. They also enjoy crops such as sweet corn and soybeans. While they mostly stay outside, they like a warm house in the winter as much as you do, and they often come inside during cold weather. They don't breed inside, but you still might want to know if you're seeing mostly male or female stink bugs.


Stink bugs on average are about 3/4 of an inch long, and their shield-like shape means they're almost as wide. When you're trying to tell stink bug genders apart, it's best to have several bugs handy so you can compare. At first glance, both genders look almost identical. Females, however, tend to be larger than males. Comparing the size of several stink bugs lets you determine which are female and which are male -- there's usually a noticeable difference in their sizes when placed side by side. This only works with mature stink bugs; different-sized nymphs might be in various growth instars, so a larger one might actually be a male that's older than a smaller female.


Of the two main stink bugs in the U.S., the brown marmorated stink bug has spots on its back that help distinguish the genders -- the green stink bug doesn't. Both female and male brown marmorated stink bugs have a dark line that goes across the widest part of their upper backs. These lines typically have light-colored spots along them. In males, these spots are raised to form bumps. In females, they're smooth. You might not want to touch a stink bug to find out about the bumps; they release their nasty odors when disturbed or scared. Using a magnifying glass might give you a close-enough look to determine whether you're looking at a male or female.


Stink bugs usually live on fruit trees, bushes or vines, although they sometimes move over to vegetables. They suck the juice out of small areas of the fruit and vegetables, leaving dark or deformed spots. If you notice these problems in your home garden, you can still eat the fruit by cutting away the damaged areas, but large stink bug populations can decimate your fruit until it's inedible. When the weather cools, the stink bugs look for warm places to spend the winter, and your house is a likely target. Stink bugs don't harm humans -- no biting or toxins left behind -- but they're difficult to eradicate and can smell up your home.


Stink bugs are resistant to many insecticides, making it difficult to get rid of them. In your home, those touched by insecticide foggers might die, but after the fog dissipates, stink bugs that were safely hidden away in cracks or behind your walls and ceilings still live. The best way to get rid of them inside is to vacuum them up; however, they often release their stench into your vacuum, and it takes a while to fade away. Using insecticides outdoors can cause the bugs to retreat into your house, and many aren't that effective against stink bugs. Look for a general insecticide that's safe for your particular fruit or vegetable and apply it as often as is safe, typically once or twice a week as needed. For example, pyrethroids are safe to use with peach trees and shouldn't harm helpful insects such as bees. Avoid insecticides containing carbaryl, chlorpyrifos or azinphosmethyl, which are highly toxic to bees.