Cactoblastis cactorum, or the cactus moth, is an invasive South American insect species that feeds on prickly pear cacti (Opunita spp.), which grows in U.S. Department of Agriculture plant hardiness zones 3 through 11. This moth currently lives in the eastern range of USDA zones 8 through 10, but is predicted to spread across the deserts of the American Southwest. Nondescript adult moths bear larvae with bright reddish-orange bodies and dark spots. Groups of larvae bore into pads to feed, causing extensive damage and even killing small plants. But you can get rid of cactus moths without using harsh chemicals.
Monitor your prickly pear plants for cactus moth larval activity and "egg sticks." The egg sticks consist of 75 to 90 eggs lined up and stacked so that they look similar to long, curved cactus spines.
Grip a larvae- or egg-infested prickly pear pad with a pair of tongs. Carefully cut the affected plant material as close to the main cactus body as possible using a large, sharp knife.
Place all removed pads into clear plastic bags and set them in direct sunlight to "cook" the larvae and eggs. Throw treated pads away in a covered trash can to prevent any surviving caterpillars from escaping and re-infesting your prickly pears.
Things You Will Need
- Large, sharp knife
- Clear plastic bags
- Covered trash can
- Because this pest exclusively feeds on prickly pears, it is sometimes referred to as the prickly pear moth.
- Early signs of cactus moth infestations include yellowing or oozing plant tissue and a powdery fecal substance littering the ground beneath the cactus.
- These gregarious eaters eventually hollow out prickly pear pads.
- Remove all prickly pears from your yard and garden areas to avoid future cactus moth infestations. The pests require this particular cactus to complete their life cycles, so won't appear if you don't have any growing in your outdoor spaces.
- Don't use any insecticides to treat cactus moths because the chemicals are generally ineffective and can harm desirable butterfly species.
- Prickly pears infested with cactus moths have low survival rates, so remove infested plant tissue as soon as possible.
- When removing infested pads, avoid cutting toward your body. Always cut away from yourself to avoid injury.
- University of Florida IFAS Extension: Cactus Moth (Cactoblastis Cactorum)
- Don't Move Firewood: Cactus Moth
- Louisiana State University Ag Center Research & Extension: Cactus Moth
- The Quiet Invasion: A Guide to Invasive Species of the Galveston Bay Area: Cactus Moth
- TexasInvasives.org: Cactoblastis Cactorum
- University of Florida IFAS Extension: Opuntia Spp. Prickly Pear Cactus
- Smithsonian Marine Station at Fort Pierce: Cactoblastis Cactorum
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