Frequently Asked Questions about Salvinia Control
Because they have been shown to work! None of the other methods-chemical, mechanical and drawdown have been shown to be effective in the long run.
Will the weevils work?
They have been shown to work at a number of sites around the world. For instance: India, Australia, Papua New Guinea, South Africa, Botswana, Kenya, Zambia, Namibia, Ghana, Malaysia (mainland Sabah, Sarawak), Fiji, New Zealand, Sri Lanka
Will this eliminate GS completely?
No. There is currently no technology that will completely eradicate salvinia. However, the weevils can reduce salvinia to the point where it is not a major problem.
How long will this take?
We hope to start rearing weevils in the spring of 2014 for introduction into the lake by that summer. How long it will actually take depends on the resources that are available and the efficiency that we are able to achieve.
Why not remove the weed from the lake mechanically?
A pilot project to mechanically remove the salvinia was tried a couple of years ago. It did work, but, was expensive and labor intensive. And the salvinia returned. Some property owners are expected to continue mechanical removal in boat houses, ramps, etc.
What is the State doing ?
The State (Parks & Wildlife) was instrumental in providing funding for the spray program. They were a significant player in building the weevil tanks at the refuge. We are anticipating that the State will partner with us as more details of the plan are put in place.
Will the spraying have to stop if you use weevils?
We expect the spray program to continue to be a part of the control program, but probably on a much smaller scale (boat ramps, docks, etc) and coordinated with the weevil releases.
Will the spray kill the weevils?
Yes, the spray that has been used on the lake will kill the weevils.
Where will you put the facility to raise them?
We are actively looking for sites.
Will the weevils eat anything else, like the cypress trees?
No, their diets consist entirely of giant salvinia. They have been used all around the world for 30 years, and have never done any harm to any other plant. They had to undergo rigorous testing before they could be brought into the U.S.
Why can’t everyone just raise their own weevils?
These little guys are very difficult to rear, especially in the large numbers we require for use on Caddo. How to raise them has been one of the purposes of the A & M research. Some of the variables that need to be controlled are temperature, water quality, ph, nutrients. Raising the salvinia weevils is a labor intensive job which requires a great deal of knowledge about their life cycle, and how to provide optimal conditions for population growth. It is not easy and it is not a part time job.
Where did the weevils come from–naturally? What about the weevils you get?
The weevil (cyrtobagous salviniae) is a native of South America, also the source of giant salvinia. We would expect to get our initial stock of weevils from south Louisiana. They have had success raising them in their warmer climate.
Texas A & M has a facility at the Refuge. Aren’t they raising them?
The A & M facility at the Refuge is a research project and is expected to remain a research project. They have not produced weevils in the quantity that will be required to control salvinia on Caddo. We need a production facility.
Won’t salt kill the salvinia?
Yes, but only at concentrations that will kill everything else in the lake.
Are we working with Louisiana?
Louisiana has its own control program, and they have a weevil program that has worked very well in the southern part of the state. In the northern part of the state, herbicides have been the main means of control; they are just beginning to look at the use of weevils. There has been some co-operation on shared water bodies, but there are not enough weevils available to treat all the infestation in Texas.