Saturday, August 31, 2013

Stink Bugs

You know you married a naturalist when she carries a little plastic box to bring home bugs from the garden.  Last week there were two stink bug gifts for me to check out.  Worse yet, I was pleased with the gifts.

Sometimes the identification of even commonly seen bugs can be difficult.  There is agreement on the name green stink bug but from there it gets a little contentious.  The green stink bug, Chinavia hilaris, is my first choice based on appearance and the little black spots along the edges.  It is the most commonly encountered stink bug in the US.  ID confirmed

Our Stink Bug- rkipfer
N. viridula  4th Instar- Wikimedia
Another contender is the southern green stink bug, (Nezara viridula), thought to have originated in Ethiopia but it is now found world wide, mainly in tropical and subtropical climes.  They are generalists but seem particularly attracted to the bean family, feeding especially when they are forming fruit or pods.  Early instars can be quite colorful.

C. hilaris Stink Gland- Cotinis

The distinction between these is based on the location and shape of the stink gland on the ventral (underside) of the bug.  It takes dedication and breath-holding to identify this.  Robert Coin has good closeups of C. hilaris which you can view odor free.   A Bugguide closeup shows N. viridula's stink gland orifice. 

Many stink bug species communicate by vibrating a leaf with their own species and sex specific "song" as described in a previous blog.  "When ready to mate N.viridula sound 100Hz vibrations with a tymbal composed of a fused first and second terga that allow bi-directional communication to any Nezara standing on the same plant so they could find each other." Wikipedia
Stink bugs feed by stabbing their needle-like proboscis into the plant, injecting toxins that damage the tissue.  Depending on the site of injury and the degree of physical and chemical damage it may just wound or even kill the plant.  Fortunately, in our garden these were apparently minor wounds.

Euschistus sp.
Euschistus sp. of brown stink bugs are native but that doesn't mean they are more desirable in your garden.  The most common species is the brown stink bug, Euschistus servus.   They are quite prolific, the females producing 18 egg masses, each with 60 eggs on average.  Multiplied by multiple generatons (5/year in Florida), their voracious appetite and strong flying traits and you have real trouble.  Fortunately lots of parasites, pathogens and predators such as our favorite assassin bugs act to keep the numbers in check.

Stink bugs eat our favorite plants, feed other insects and eventually their stored energy passes on to birds and higher predators.  It all works out in the end.
Green stink bug eggs- Chris Barnhart

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