Weevils & Water Hyacinth


Your home garden pond offers habitation to wildlife and tranquility to your landscape but can easily fall under attack by the beautiful yet harmful plant pest water hyacinth. Preventing the development of problems in your pond is essential to leaving the balance of plant and animal life undisturbed. Familiarize yourself with this free-floating aquatic perennial for the continued health of your pond.

Plant Description

Water hyacinth plants (Eichhoria crassipes) are aquatic perennial flowering plants that display deep green leaves and light violet/blue spiked flowers. They are floating plants with root systems that thrive beneath the water's surface. Water hyacinth reaches a height of 3 feet.

Infestation Effects

Water hyacinth is considered a pest plant that needs management. Weevils are one method of control. Once water hyacinth plants appear on your pond's surface, they can quickly cover the entire surface as aggressive spreaders. Though visually pleasing, the inundation creates a dangerous environment because the plant coverage suffocates other life within your pond by blocking out sun and air, according to Texas A&M. Water hyacinths do not simply float individually but cause severe problems because of their matting habit.

Weevil Types

Water hyacinth weevils (Neochetina eichhorniae) offer biological control of water hyacinths on pond surfaces, according to the U.S. Army Corps of Engineers Environmental Laboratory. Both mottled and chevroned water hyacinth weevils offer protection. The mottled weevil has a brown/red to gray body with a "mottled" color pattern. The chevron weevil is pale brown with a repeated V-shaped pattern.


Through placement of weevils on water hyacinth plants, adult females chew a hole into the plant to lay an egg. Within 10 days, the egg hatches and the larval weevil begins chewing on the water hyacinth, eventually demolishing the plant's bud. Adult water hyacinth weevils also feed on plant tissue, according to the Army Corps of Engineers. This method of control is not immediate, but weevil infestation of water hyacinth leads to stunted plant growth and decreases plant dominance and spread over your pond. Substantial effects take approximately three to five years.


Though three to five years is a considerable amount of wait time, using a biological control method is environmentally friendly and effective. If you choose to use weevils to combat water hyacinth, allow adequate time and remain patient. Avoid applying chemicals as a means of speeding the process; this will disrupt and possibly ruin the potential control weevils provide, according to the Army Corps of Engineers.

Keywords: water hyacinth plant, water hyacinth weevil, water hyacinth control

About this Author

Tarah Damask's writing career, beginning in 2003, includes experience as a fashion writer/editor for Neiman Marcus, short fiction publications in "North Texas Review," a self-published novel, band biographies, charter school curriculum, and articles for eHow. She has a love for words and is an avid observer. Damask holds a Master of Arts in English and creative writing from the University of North Texas.