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Invasives Alert!

Cactoblastis cactorum
(Cactus moth)

Summary: Insect invader increasing range
The cactus moth, Cactoblastis cactorum, known best as a biological control success in places like Australia and South Africa, is now established in North America and the Caribbean where it poses a critical threat to the vast biodiversity of native prickly pear cacti. If you have any Opuntia species in your area, please look for egg sticks of the moth laid on the ends of cactus spines (looking very much like spines). Also look for the larvae, which are bright orange with orange spots or lines. The larvae burrow into and then hollow out cactus pads. The adult moth is much less easy to identify. See pictures at:

Please Help! If you know of or find infestations in your area, particularly if the sites are inland or in front of the leading edge, please contact:
Dr. Stephen Hight
Tel.: 850-412-7262
Fax: 850-412-7263

The moth is native to northern Argentina, Uruguay, Paraguay, and southern Brazil. Its larvae feed on many species of Opuntia cactus, primarily from the subgenus Platyopuntia. Opuntias are a diverse group in North America, with many endemics. There are 31 likely host Opuntia species for the moth across the U.S. (9 endemic), and 56 in Mexico (38 endemic). According to Britton and Rose (1963), there are 22 native species of Platyopuntia in the Caribbean and 17 in Central America.

Cactoblastis cactorum was first recorded in the Florida Keys in 1989, where it has already significantly reduced the native prickly pears. Since then it has moved northward up the coastline of Florida, and is moving rapidly around the Gulf Coast. As of July 2002, the moth has been documented to be as far north as Charleston, South Carolina along the Atlantic coast and as far northwest as Alligator Point, FL (south of Tallahassee, FL and about 200 miles east of the Alabama state line) along the Gulf coast. We do not know the range limits of the moth in more inland areas. USDA researchers are working to develop a sterile male release program that might be used to slow or contain its distribution. However, USDA needs to understand its distribution so that they can act quickly when the technique is fully developed. Until that time, we may need to manually protect rare Opuntia species by removing the egg sticks and infested pads.

--Doria Gordon/TNC; August 2002

Updated January 2005
©The Nature Conservancy, 2002