Conflicting Reports on Stink Bugs’ Mortality Rate Due to Our Cold Winter

stinkbug_frederick_md2In February of this year (2014), Virginia Tech researchers did studies to test stink bugs’ resilience in extreme cold temperatures. According to their research they concluded, “…about 95 percent of them were exterminated (when temperatures hovered around zero degrees for several days)”, due to the renowned “polar vortex” much of the Northeast experienced extreme cold for a longer than average duration. The research, unfortunately, was only limited to Blacksburg, Virginia where temperatures were closer to the zero degree mark, unlike Maryland.

stinkbug_frederick_md1According to another article by the Washington Post, Mike Raupp disputed the mortality rate of stink bugs. He remained more guarded in his prediction of the stink bug population in Maryland. While Blacksburg had a few days at 4 degrees below zero, Maryland did not. A research entomologist for the Agriculture Department also believes that stink bugs were not as greatly affected by the colder than average winter. Entomologist Tracey Leskey stated, “Unfortunately, they’re (stink bugs) doing just fine”. According to Leskey, “Even if they did die in bunches, they enter winter with an enormous population, so plenty of survivors rush out in spring to multiply”. Compounding the lower than expected mortality rates of stink bugs in the elements is the fact that many stink bugs make their way into homes during the cold months. Mike Raupp stated, “Every day I’ve had a stink bug wandering across my desk; they’re doing fine in my house”.

stinkbug_frederick_md3Just last week we had a customer reporting a large number of stink bugs on his house.  He noticed hey were smaller than usual, but stinkbugs nonetheless. This created the potential for an explosion of the stink bug population on this customer’s property, as there were now 2 generations of stink bugs (adult stink bugs and nymph stink bugs). A nymph (stink bug) looks extremely different than an adult stink bug; in most cases it looks so dissimilar that people think they are seeing an immature tick or other small insects. According to a research article, the brown marmorated stink bug, or BMSB, has a life cycle which consists of the following:

Eggs: The white or pale green barrel-shaped eggs are laid in clusters on the undersides of leaves. Egg masses have about 25 eggs that are only about 1 mm in diameter but become apparent when nymphs have recently emerged, as they will stay at the egg mass for several days. In Pennsylvania, eggs first appeared in late June, but females continued to lay egg masses until September. Although only one generation was observed, multiple generations are likely as the distribution spreads to the south (Bernon et al. 2004).

Nymphs: As with all immature stink bugs, the nymphs lack fully developed wings and have been described as tick-like in appearance, ranging in size from 2.4 mm (1st instar) to 12 mm (5th instar). Nymphs need to molt, or shed their outer skin (exoskeleton), as they progress through five different stages or nymphal instars. First instars are colored orange or red and remain clustered around the egg mass, sometimes until they molt to the 2nd instar stage. The 2nd instar begins to develop an almost black appearance, and subsequent instars (3rd, 4th, and 5th) begin to acquire more of the adult BMSB coloration.

Adults: Adults are 12 to17 mm long (approximately 1/2 inch), and have a mottled appearance. Alternating dark and light bands occur on the last two antennal segments. Additionally, the head and pronotum are covered with patches of coppery or bluish metallic-colored punctures and the margins of the pronotum are smooth as compared to the toothed, jagged pronotal margin of Brochymena (Hoebeke 2002). The exposed lateral margins of the abdomen are marked with alternate bands of brown and white. Faint white bands are also evident on the legs.

Don’t let stink bugs take over your house, refer to our previous blog about the best way to remove them from your home. As always, if you have any questions regarding stink bugs and how to best protect your home, call us at (301) 263-7220.

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