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Fighting the Water Hyacinth


State releases insect to combat invasive weed

AP/San Jose Mercury News


SACRAMENTO — California officials have deployed thousands of insects native to South America in the San Joaquin-Sacramento River Delta to combat an invasive weed that has clogged the waterway.

Scientists released more than 5,000 water hyacinth plant hoppers at several locations in San Joaquin and Sacramento counties this month, the state Department of Food and Agriculture announced on Thursday.

Officials hope the insects will establish self-sustaining colonies and begin chomping down on water hyacinth. The invasive plant forms a dense carpet on the surface of waterways, impeding boat access and clogging water intake systems.

Historically, importing animals to control other animals has backfired substantially at times, especially with mammals. Insects that are specialized to attack only one other species are more ideal, but it’s still a gamble when bringing them to someplace far away. Hopefully the water hyacinth plant hoppers (these are presumably leafhoppers of some kind) won’t take a liking to some native, non-invasive plant species.

California Department of Food and Agriculture news release from two days ago:



Initial releases of 750 water hyacinth plant hoppers were made earlier this month in three locations: Whiskey Slough in San Joaquin County, Willow Creek in eastern Sacramento County, and Seven Mile Slough in western Sacramento County. Secondary releases have since been made in Whiskey Slough (1,500 insects) and Willow Creek (3,000 insects). Scientists hope the plant hoppers will thrive in their new home, eventually resulting in self-sustaining colonies. This project shows CDFA’s ongoing commitment to the principles of integrated pest management – considering physical and biological approaches and using them whenever possible.

Before a biological control agent like the water hyacinth plant hopper can be released in California, the organism must be cleared by both federal and state regulatory officials through an exhaustive analysis that weighs risks. Biological control agents from outside the U.S. are shipped to a domestic quarantine facility where they are subjected to a series of tests. Only those organisms with high specificity to the target weed are approved for use as biological control agents. The results of the pre-release tests are summarized into a petition requesting permission to release the organism into the field. Once approved, the permitted biological control organism can be mass-reared to high numbers and released at field sites established by biologists.

The water hyacinth plant hopper, known to scientists as Megamelus scutellaris, is approximately 1/8 inch in length as an adult. It feeds only on water hyacinth, making it an ideal candidate for release as a biological control agent. The insects feed on water hyacinth leaves by siphoning plant juices into their mouths, much like an aphid on a rose bush. The damage caused by their feeding kills the small area where their siphons are inserted; high densities of plant hoppers and high levels of feeding can cause whole leaves to wilt and die, reducing the infestation and relieving pressure on the waterways.

You can see pictures of them here.


One Response to “Fighting the Water Hyacinth”

  1. I’m curious, was there research conducted on what possible impact this insect can have on the environment as well?


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