The Cactus Moth Detection and Monitoring Network (CMDMN)
The Cactus moth (Cactoblastis cactorum Berg.) is a widely used biological control agent of pricklypear cactus in Australia and South Africa. Cactus moth appeared in the Florida Keys in 1989, spreading as far as South Carolina and Louisiana. Cactus moth quickly destroys a stand of pricklypear, and is a threat to natural biodiversity, horticulture, and forage in the southwestern United States and Mexico.
In the effort to monitor the progress of the cactus moth, sentinel sites have been established along the leading edge. These sites are monitored on a regular basis for the presence of the cactus moth.
Scientific Name: Cactoblastis cactorum
(Berg) (Insecta: Lepidoptera: Pyralidae)
Common Name: Cactus moth
Native To: Argentina
Introduced To: Australia, Hawaii, India, South Africa, and the Caribbean
Invaded: The southeastern U.S. and threatens Mexico
Host Plants: Pricklypear cacti ( Opuntia spp.)
Damage: Total destruction of plant
Dissemination: Adult moths can fly (distance unknown). Storm (hurricane) winds can carry adults. Investations can spread by consumers through nurserys and by transplanting from one area to another.
Threatens: Rangeland grazing, nursery plants and landscaping, production of fruits, pads, and cochineal dyes for human use, desert ecosystems and biodiversity, human welfare and economy of the southwestern U.S. and Mexico.
Originally from Argentina, Cactoblastis was found to be one of the most successful biological control agents in history. After being introduced into Australia in the 1920s, the cactus moth drastically reduced the exotic and invasive pricklypear cacti. For Australia, control of the Opuntia populations was a necessity in order to convert large areas of land back to agriculture.
For similar controls, the moth was introduced in India (year uncertain), South Africa in 1933, and Hawaii in 1950. Then in 1956, the cactus moth was introduced to the Caribbean island of Nevis from where it spread to the other islands. Eventually, the invader was detected in the Florida Keys in 1989, and may have been introduced as a hitchhiker on ornamental cacti imported from one of the Caribbean islands. Today, free-living populations are found as far north as Bull Island, South Carolina along the Atlantic Coast and as far west as east Louisiana along the Gulf Coast. It appears that cactus moth populations are concentrated on barrier islands and coastal areas of the Atlantic and Gulf Coasts.
Ironically, what was a control agent has become an invasive species that threatens native and endemic pricklypears as well as the cactus industry and desert ecosystems of the Southwest and Mexico. The cactus moth in the United States, directly threatens a total of 31 species of native pricklypear cacti plus numerous other native species associated with cacti. In Mexico, 53 species of pricklypear are threatened, including 38 endemic species.
The female moth lays eggs stacked on top of each other like pancakes to form an "egg stick" that resembles a cactus spine. Each female can lay 60-100 eggs in a single egg stick and can lay 200-300 eggs within a few days. Egg sticks are about an inch long and are usually on the undersides or other protected parts of the plant pads. The egg stage lasts 3-4 weeks. The caterpillars burrow into a pad after hatching and feed together as a group. The infestation by the lightly colored young larvae may be difficult to detect without splitting the pad open.
As the larvae mature, frass and sap may be pushed out of openings in the pad and onto the ground. Eventually the pad will become transparent and hollow. Larvae may move to additional pads to complete development, especially if the initially infested pad is small. Larvae mature in 4-5 weeks. Mature larvae leave the plant and pupate under dead leaves or between the pads where they spin white cocoons. The pupal stage lasts 15-20 days. They emerge as adult moths and the cycle starts over.
Symptoms of internal feeding on pricklypear can be seen at anytime of the year, however, larvae may be difficult to find during the colder months. Larvae tend to congregate in the lower parts of the plant and are not seen feeding in galleries when it is cold. If daytime temperatures reach a certain point, larvae will migrate to the upper cactus pads, and even sometimes be seen on the exterior of the pad on the sunny side of the plant.
In Argentina, Australia, and South Africa, Cactoblastis normally undergoes two generations per year. However, on the U.S Gulf Coast, the cactus moth has been observed having three generations per year. The extra generation is contributed to the warmer climte. Adult flight and mating periods are as follows:
- 1st flight period - late March through May
- 2nd flight period - July through August
- 3rd flight period - late September through mid-November
The pricklypear cactus is a cultural icon in Mexico where its image is on the Mexican flag and coins. Pricklypears are commonly relied upon as food as the fruit are processed into jam and syrup while the plant itself is commonly boiled or pickled. The cactus has its place in the pharmaceutical market as well as cattle fodder mainly during the dry years. Cactus is a $50 million to $100 million a year industry in Mexico. In the U.S., it is estimated that pricklypear cactus has a trade, nursery, landscape, crop, and forage value of up to $70 million a year, mainly in the Southwest. Environmentally, cacti prevent erosion and are a habitat and food source for many species of invertebrate, birds, mammals and other animals.
Pricklypear cactus is an important plant resource to the U.S. nursery and landscape industry. The growth of xeriscape landscape design in high population growth areas such as Phoenix and Tucson, Arizona, and Las Vegas,Nevada, has been promoted by state and local governments. In Arizona alone, the ornamental pricklypear cactus industry encompasses over half a million plants with a wholesale and retail value estimated to be more than $15 million.
Other impacts on the economic effects can be found in a USDA-PPQ white paper.
View the destruction gallery.
Infestation by Cactoblastis may be indicated by the presence of egg-sticks, which resemble cactus spines. However, native cactus-feeding Lepidoptera lay similar egg sticks that currently cannot be distinguished reliably from those of the cactus moth. Identification has to wait until the larvae appear.
The mature larvae are more distinct with a characteristic orange to red color interrupted by dark banding or spots on the body and are relatively easy to distinguish from those of native species. However, younger stages of Cactoblastis are similar to those of native species and the two sometimes have been misidentified. Available larval identification keys are limited to differences in color of mature larvae. Also, records of some species may only be known from limited reference material. If you suspect the presence of the cactus moth, please view important information below.
The adult cactus moths are non-descript brownish-gray moths that can only be definitively identified by a microscopic examination of dissected male genitalia, although the native species differ from Cactoblastis in having a more plumose antenna. Click on the moth image to the right for a comparison between the native moth Melitara and Cactoblastis. High resolution images are also provided for Melitara and the Cactoblastis.
They generally appear as typical pyralid moths with pronounced labial palps of the female, thus the name "snout moths". The forewings show a characteristic banding pattern, however other related Phycitinae have similar banding. If you suspect the presence of the cactus moth, please view important information below.
Additional Help for Identification
For more information and a key to the cactus feeding species in the Southeastern US, see:
Solis, M. Alma, Stephen D. Hight, and Doria R. Gordon. 2004. Tracking the Cactus Moth, Cactoblastis cactorum Berg., as it flies and eats its way westward in the U.S. News of the Lepidopterists Society 46(1) 2-3.
Do you suspect the presence of the cactus moth?
Knowing where the cactus moth are located is critical in the efforts to monitor and control its spread. Please do not disregard the importance of proper notification and identification. If you suspect your pricklypear cactus is infested by the cactus moth, please notify Dr. Victor Maddox and Dr. Richard Brown at Mississippi State University. Dr. Maddox will collect information about your cactus species and Dr. Brown will perform the identifications on insect samples that are submitted.
Insect samples should be prepared before shipping. Larvae encountered on pricklypear should be collected, killed in boiling water, and preserved in 70% ethyl alcohol or by following specific instructions from Dr. Brown. These should be sent, with all collection information and any digital photos, to Dr. Richard Brown (contact information below). Information about confirmed infestations will be provided to appropriate state and federal officials who will determine a proper course of action for addressing the problem.
Dr. Brown is also interested in receiving specimens of any Lepidoptera found on pricklypear in the U.S., including different stages, accompanied by adults reared out from larval collections. Digital photos of live larvae will also be helpful in documenting color variations and providing future visual keys to surveyors.
Dr. Richard Brown, Director
Mississippi Entomological Museum
Box 9775 (103 Clay Lyle for FEDEX/UPS)
Mississippi State, MS 39762
Phone: 662-325-2085 Email: email@example.com
Pricklypear cacti belong to the Cactaceae Family and the Genus Opuntia. In the United States, it is a large genus of cacti with approximately 93 species. The genus Opuntia consists of all pricklypear cacti, those having flat-pad stem forms, or cladodes.
The list of known hosts for Cactoblastis cactorum (the cactus moth) are pricklypear cactus species, in the genus Opuntia, with the exception of a few records from one species in the related genus, Nopalea. While other host records appear in the literature, none of these records of the cactus moth attacking any other cactus species are reliable. Cylindropuntia are not thought to be hosts. Another related genus, Grusonia, appears in older literature as Opuntia, but species in that genus are also not known to be hosts. Images are available to help the identification of some of the most common Opuntia species within the southeastern U.S. See the table below for a list of all native Opuntia species (within the Platyopuntia group). Many ornamental species found in nurseries or used in landscaping are native but, others may be from Mexico or South America. (Naturalized indicated by *)
|Species / State||AL||AZ||CA||CO||FL||LA||MS||NM||NV||TX||UT|
(syn. Nopalea cochenillifera)
(Syn. Consolea corallicola)
Images to help identify the most common species within the southeastern U.S.
To prevent further spread of cactus moth in the U.S., it is very important to detect, report and rapidly respond to all new outbreaks of the pest. The first priority must be to make a serious attempt to eradicate such infestations.
Be aware there are a number of native species of Lepidoptera larvae that can be found feeding on pricklypear and may be confused with Cactoblastis cactorum. These native species are not considered a threat to the pricklypear population. Correct identification by a qualified entomologist is important. Please refer to the Identification section for what to do if you suspect a cactus moth infestation.
Sterile insect release technology and other control methods are being developed and tested by the USDA Agriculture Research Service and other groups. Effective control of the cactus moth using insecticides is still in the testing phase and is proving difficult. Since the larvae spends most of its time within the cactus pad, insecticides are having little effect. Confirmed infestations should be eradicated by manual removal and destruction of egg-sticks and infected cacti stems.
Invasive species are a significant problem for terrestrial and aquatic ecosystems in the United States, degrading their biodiversity and the ecosystem services they provide to our society. Despite this, little attention has been directed to this significant problem until the last decade, when federal and state governments and nongovernmental organizations alike have suddenly become painfully aware of this burgeoning problem.
While the awareness of the problem has been widespread, the reaction to this threat has not been uniform, and tools to deal with these problems are restricted. In particular, response within the Mid-South states lags behind that of other regions where more resources have been allocated towards dealing with invasive species.
Mississippi State University is developing and implementing a program of planned research, extension, and regional coordination to address these needs. Our approach is multidisciplinary, and involves biologists, ecologists, computer scientists, economists, engineers, and others acting together as a research team.
Graduate and summer student opportunities are available. Students interested in educational opportunities should view the Invasive Species Program Poster for more information, or send a general inquiry to:
Dr. John D. Madsen
Box 9652, Mississippi State, MS 39762-9652
Ph: 662-325-2428, Fax: 662-325-7692
The ability to monitor the spread of the cactus moth entirely rests on knowing where cacti are located. Information is urgently needed on locations where native and ornamental varieties of cacti are known to occur in the Mid-South. Information on cactus locations can be sent to Dr. Victor Maddox. Cactus plants that are within 30 meters of one another are considered the same population. Information that is needed on each cactus population is as follows:
- Physical Address (or the best of one you can provide)
- GPS Location of Cactus
- Land Use (Natural, Residential, Commercial, Agricultural, Nursery)
- Ownership (Private, Local, County, State, Federal Agency)
- Contact Person for the Population (Name, Address, Phone)
- Species of Cactus (if not known, please provide good digital photos)
- Approximate Number of Plants
- Size of Population Area (# acres, # sqft)
- Do You Suspect the Cactus Moth is Present?
If you are interested in volunteering, providing cactus information, or just for more information on how you can help, please contact:
Dr. Victor Madddox
Box 9555, Mississippi State, MS 39762-9555
- Cactus Moth Survey Manual
- Information about collecting survey information for cactus locations, visual observations for the cactus moth, and trap monitoring stations.
- Cactus Moth Detection Network Fact Sheet
- Fact sheet on the Early Detection and Reporting of Cactus Moth in the U.S.
- Cactus Moth Brochure
- A tri-fold brochure on the cactus moth used as handouts in information packets.
- Opuntia Handout
- A handout used to inform the public of the need to locate populations of Opuntia Cacti and describes how the public can help in that effort.
- PEST ALERT: Cactus moth Cactoblastis cactorum (APHIS PPQ)
- DiscoverLife's online Opuntia Identification Guide
- The Nature Conservancy - Global Invasive Species Initiative Cactus Moth Alert
- National Invasive Species Council's Cactus Moth Information
Our major partners are U.S. Geological Survey Biological Resources Division (USGS BRD), National Biological Information Infrastructure (NBII), and the U.S. Department of Agriculture Animal and Plant Health Inspection Service Plant Protection and Quarantine (USDA APHIS PPQ). Please visit the USDA APHIS PPQ Cactoblastis Management Program website for more information about the overall cactus moth program.
Our Partners (Cactus moth and Opuntia resources from our partners will be listed under Resources.)
USDA-APHIS has a volunteer coordinator in the Gulf Coast area, and there are USDA Pest Survey Specialists that cover various regions of the U.S. conducting surveys for various pests. If you need personal assistance, please contact Joel Floyd or go to the following URL to obtain contact information for the Pest Survey Specialists covering your area.
John D. Madsen, Ph.D.
Mississippi State University
Mississippi State, MS 39762-9652
ph. 662-325-2428 fax 662-325-7692
Victor Maddox, Ph.D.
Mississippi State, MS 39762-9555
Cactus Moth Identification
Richard L. Brown, Ph.D.
Department of Entomology & Plant Pathology
Box 9775 (103 Clay Lyle for FEDEX/UPS)
Mississippi State, MS 39762-9775
Web Database System, Webmaster
Mississippi State, MS 39762-9652
USDA Cactus Moth Program
USDA, APHIS, PPQ
4700 River Road, Unit 137
Riverdale, MD 20782
Coordinator for Federal, Public,
and Private Conservation Lands
Randy G. Westbrooks, Ph.D.
USGS BRD - National Wetlands Research Center
233 Border Belt Drive
Whiteville, NC 28472