What's That Bug? does not endorse extermination

What’s ON that bug? Ranatra w/ orange bumps
Thu, Jul 2, 2009 at 3:12 PM
I recently tracked down the ID of this odd insect in a local pond as a Water Scorpion (Ranatra spp.), but all of the individuals I’ve seen so far are covered in strange, orange bumps that do not appear to be “normal” or common. Do you have any idea what these might be caused by? The pond is next to the building I work in and appears to be the result of dam work by the local beaver’s union. There is plenty of food for these guys with damsel flies, tadpoles in the thousands and other small, crunchy things. The other wildlife in the area does not appear to be suffering from any apparent disease or sicknesses and the vegetation around the pond appears to be thriving.
Eric Snyder
Issaquah, WA 98027

Water Scorpion with Phoretic Mites

Water Scorpion with Phoretic Mites

Hi Eric,
Congratulations on identifying the Water Scorpion in the genus Ranatra.  That is not an easy identification.  The orange bumps are Aquatic Mites.  The Aquatic Mites often use flying aquatic insects to get from one body of water to another, a behavior known a phoresy.  Some time back when we posted an image of a ToeBiter with mites, we got this comment from a reader.

Previous Comment on similar posting:  Mites on the toe-biter?
Hi Daniel and Lisa Anne,
About the email on the Toe Biter from Tom on (01/27/2007) who talks about having 12 red mites on his Toe Biter? I remember seeing mites on aquatic insects, looking suspicious, and so I looked it up, and it turns out that *all* of the more than 5,000 known species of aquatic mites (Hydracarina) are partly parasitic. When they are larvae, aquatic mites are parasitic on aquatic insects, but as adults the mites become free-swimming and predatory. Winged aquatic insects, such as the toe biters, fly around of course, and that way the mites are spread from one body of water to another. You can read a lot more interesting stuff about them at:
http://www.tolweb.org/Parasitengona
And at :
http://www.tolweb.org/Hydracarina
Best to you as always,
Susan J. Hewitt

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What's That Bug? does not endorse extermination

One Response to Aquatic Mites on Water Scorpion

  1. bmoc says:

    The mites are in the family Hydrachnidae, genus Hydrachna. They very typically parasitize aquatic Hemiptera.

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