Learning why that is - what ecological conditions make it produce only sterile seeds - could be key to developing further preventative measures against it. Biological measures Insects have been released for the biological control of A. philoxeroides. The most successful and widely used is Agasicles hygrophila commonly called the alligator weed flea beetle; it has been released for biocontrol in Australia, China, Thailand, New Zealand, and the United States. However, their effectiveness is limited due to their inability to survive through temperatures lower than . Amynothrips andersoni, the alligator weed thrips, and Vogtia malloi, the alligator weed stem borer, have also been released in the United States. These species result in immediate wilting and limit A. philoxeroides reproduction by colonizing its stems. A variety of chemicals have been shown to be effective in controlling the plant, the most useful of which include glyphosate, triclopyr, fluridone, imazamox, and imazapyr; however, they must constantly be applied to be successful. Legality of sale and shipment in the United States In 1956 A. philoxeroides was banned for sale or shipment in the United States, subject to a fine and/or imprisonment. This law was repealed by HR133 [116th Congress (2019-2020)] on 12/27/2020. See also Ludwigia grandiflora References External links The evolutionary history of an invasive species: alligator weed, Alternanthera philoxeroides, XII International Symposium on Biological Control of Weeds Pest Plant Risk Assessment: Alligatorweed, Biosecurity Queensland, Department of Employment, Economic Development and Innovation Species Profile - Alligatorweed (Alternanthera philoxeroides), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Alligatorweed. Alternanthera philoxeroides (Mart.) Griseb. Medicinal Plant Images Database (School of Chinese Medicine, Hong Kong Baptist University) philoxeroides Aquatic plants Flora of South America