Nevada Fish & Wildlife Office
Pacific Southwest Region

Ash Meadows Naucorid
(Ambrysus amargosus)

Class: Insecta
Order: Hemiptera
Family: Naucoridae
Genus: Ambrysus
Species: amargosus
Max Length: 6.5 mm
Feed: aquatic insects and crustaceans
  • Small insect that is oval and flat
  • Dark brown coloration
  • Modified fang-like front legs to capture prey
    Official Status:

    The Ash Meadows naucorid was first listed on May 20, 1985 . It is currently designated as Threatened in the Entire Range .

    Life History:
    The Ash Meadows naucorid is a predatory insect that lives entirely underwater. It clings to rocks in riffle habitat in warm spring outflows and hunts a variety of aquatic insects and crustaceans. The naucorid has several life stages known as instars, and has both juvenile and adult forms.
    Distribution and Habitat:
      It has been found only at Point of Rock5 Springs and their outflow streams. It is a small aquatic insect reaching about 6 mm in length that is apparently unable to fly.

    The Ash Meadows naucorid is found only in flowing water associated with Point of Rocks Springs in east-central Ash Meadows. Its remaining habitat is greatly reduced from that known to have existed historically because of channelization of the springs' outflow for agricultural diversion, and because of large-scale alteration of the Point of Rocks Springs area when PEC impounded approximately 90 percent of the flowing water. This species is now restricted to several stream channels less than 0.3 meters wide and 10 meters long. Threats to its livelihood include ground water depletion decreasing spring discharge, and extremely limited range making it susceptible to decline because of a single event disturbing its habitat or causing mortality. All of the remaining habitat of this species occurs within land purchased to established the Ash Meadows National Wildlife Refuge.

    Fun Fact:
      One way which Ambrysus breathe is using a bubble of air stored on their abdomen. This bubble acts as a 'lung' in which it exchanges gas with the surrounding water. Juvenile naucorids absorb oxygen through their cuticle (skin).
    Last updated: April 16, 2014