Wednesday, May 22, 2013

Polistes metricus

Paper wasps tend to be quite variable in color and pattern, even within one species, so identifying them is not easy, even for experts. Case in point is differentiating the common Northern Paper Wasp, Polistes fuscatus, from the very similar Polistes metricus.

Dark specimens of the Northern Paper Wasp are nearly identical to Polistes metricus, a consistently dark species that I have found to be less abundant than P. fuscatus in areas where their geographic ranges overlap. One fairly reliable, if subtle, clue is the shape of the abdomen. Note that the abdomen of P. metricus is highly convex on the underside, creating a nearly acute angle with the underside of the petiole (stalk-like segment connecting abdomen with thorax). This is usually much less pronounced in P. fuscatus.

Another difference is in the face of the female wasps. Females of P. metricus have an almost completely red face, the black markings confined to the ocellar triangle. Ok, so what is an “ocellar triangle?” Most wasps have a trio of tiny, “simple” eyes at the top of the head, between the large compound eyes. These simple eyes are usually arranged in a triangular pattern. Females of the Northern Paper Wasp have the black marking extended from the ocelli to the base of the antennae. Males of both species have square, yellow faces.


Female P. fuscatus. Note black face; gently curved venter of abdomen

Female P. metricus. Note convex venter of abdomen.

Female P. metricus. Note all-red face.

Polistes metricus ranges from extreme southwestern Ontario and Maine south to Florida, and west to southern Ohio, Nebraska, Kansas, Oklahoma, and eastern Texas. The Northern Paper Wasp has a much larger geographic distribution.

I was fortunate enough to find three embryonic nests of P. metricus on a recent trip to Missouri. Two nests were under the exterior of a recessed door frame in Excelsior Springs. The other was under the roof of a sign and kiosk at Little Dixie Lake Conservation Area west of Kingdom City. These are typical nesting sites, though they can also be built among shrubbery and other more exposed locations.

Both the Northern Paper Wasp and P. metricus prey mostly on caterpillars, chewing up the larvae and feeding them to their own grubs back at the nest. Look for the adult wasps on flowers as they fuel themselves on nectar. They can also be seen around aphid colonies, lapping up the “honeydew” secreted by the aphids as a waste product.

Source: Buck, M., Marshall, S.A. and Cheung D.K.B. 2008. Identification Atlas of the Vespidae (Hymenoptera, Aculeata) of the northeastern Nearctic region. Canadian Journal of Arthropod Identification No. 5: 492 pp. (PDF version).

5 comments:

  1. I have recently encountered 2 different nests of these dark wasps while clearing brush from my property here in east Texas. Might I mention that these wasps become very aggressive when bothered by someone shaking bushes near their nest! Furthermore; they have a nasty, painful sting! A word to the wise,,,,have Benadryl handy before cutting brush in east Texas!!

    ReplyDelete
  2. This comment has been removed by a blog administrator.

    ReplyDelete
    Replies
    1. This comment has been removed by the author.

      Delete
    2. The comment above was probably an attempt at spam.

      But I have a question which I hope you can answer. I recently ID'd a Polistes metricus for someone in Texas who was very afraid (I am not in Texas). Someone else came in and claimed it was a "Mahogany Wasp" which she further claimed are super aggressive (like if you breathe in the same town as them they will chase you down).

      I decided to do some research and could find no scientific name for "Mahogany Wasp" but did find one forum with 80+ responses about how mean the "Red Wasp" (which is apparently more orange than red) is.

      So wondering if you have any experience or knowledge of any of this.

      Thank you for your time. :)

      Delete
    3. Sabine: I have heard the same rumors about Polistes carolina/perplexus, but I have spent very little time in the southeast U.S. and have never come across a nest of them. So, I cannot speak to that. I strongly suspect such assessments of their temperament are greatly exaggerated.

      Delete