Tamarisk beetle die-off not saving as much water as expected

The tamarisk beetle, introduced a decade ago to try to beat back an invasive tree clogging western rivers, has not saved as much water as hoped, according to new research by a team led by the USGS’s Pamela Nagler. Nagler and her colleagues used satellite data to estimate tamarisk water use before and after the beetle’s arrival. They found

  • tamarisk wasn’t using as much water as folks had thought
  • tamarisk water use post-beetle was higher than expected because “tamarisk stands tend to regrow new leaves after defoliation and other plants help maintain canopy cover”

We’re not at equilibrium yet, as the beetle keeps expanding its range. More study needed.

H/t the invaluable Brett Walton’s Federal Water Tap.


  1. Are we surprised that the exotic beetle imported from Asia is not doing much to reduce water use by Tamarisk? Are we surprised that Tamarisk uses less water than we thought? In fact, before the beetle was released, there was substantial science supporting the notion that a dense stand of salt cedar used about as much water as a field of alfalfa. I guess we will eventually learn that introducing exotic species is not the smartest thing to do.

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