common name: tortoise beetle
scientific name: Chelymorpha cribraria (Fabricius) (Insecta: Coleoptera: Chrysomelidae)
Introduction - Distribution - Identification - Biology - Hosts - Acknowledgments - Selected References
In September of 1993, a single specimen of an exotic tortoise beetle was collected on a species of Ipomoea (Convolvulaceae) in a weedy lot in Davie, Broward County. Further collecting turned up additional specimens at the original site and at other localities in Broward County. The beetle was identified as Chelymorpha cribraria (Fabricius), a widely distributed Neotropical species known to feed on sweet potato (Ipomoea batatas (L.) Lam.) and other morning glories. Subsequent surveys and collecting have revealed populations of Chelymorpha cribraria at other localities in Dade and Monroe counties.
Figure 1. Adult of the tortoise beetle, Chelymorpha cribraria (Fabricius), with antennae and legs extended. Photograph by Jeffrey Lotz, Division of Plant Industry.
This species is distributed throughout South America and the Antilles. Buzzi (1988) recorded Chelymorpha cribraria from Brazil, Cayenne, Colombia, Guadeloupe, and Paraguay. There are specimens in the Florida State Collection of Arthropods from Antigua, Argentina, Dominican Republic, and Panama. In Florida, it has been collected in the following localities: Broward County - Davie, Hallandale; Dade County - Camp Mahachee, Cape Florida State Park, Matheson Hammock, Virginia Key; Monroe County - Key Largo State Botanical Site.
The genus Chelymorpha Boheman contains more than 100 species, which are mostly Neotropical in distribution. Two species have been recorded (Blatchley 1924) previously from Florida: Chelymorpha cassidea (Fabricius) and Chelymorpha geniculata Boheman. The endemic Florida Chelymorpha geniculata has had a checkered taxonomic history. It is often considered either a synonym or subspecies of Chelymorpha cassidea (Balbaugh and Hays 1972). Both are uniformly tan to red-brown in color with 12 to 14 black spots on the elytra and four to six on the pronotum. Chelymorpha cribraria is extremely polymorphic in color (Vasconcellos-Neto 1988), and most of the color forms have been described as separate species. Only two color forms have been found in Florida so far. The most common color form in Florida is bicolored, with pronotum black and elytra brick-red or tan. Much less common is the color form having a tan ground color with metallic reflections, numerous black speckles, and longitudinal red stripes on the elytra.
Figure 2. Adult of the tortoise beetle, Chelymorpha cribraria (Fabricius), with antennae and legs drawn in. Photograph by James Castner, University of Florida.
Vasconcellos-Neto (1988) presented a model consisting of six tightly-linked genes responsible for color in Chelymorpha cribraria. He found eight color forms produced from 21 genotypes, and hypothesized that the stable polymorphism in Chelymorpha cribraria is maintained "... by selection through visually oriented predators." Adult Chelymorpha cribraria are unpalatable to some predators. In Brazil, Chelymorpha cribraria appears to belong to at least six different mimicry groups with two to four beetle species in each group.
Buzzi (1988) reviewed the biology of Neotropical cassidines and gave the following composite account of several species of Brazilian Chelymorpha, including Chelymorpha cribraria: Eggs are glued to leaves of the host plant in clusters; they hatch in six to eight days. There are five larval instars and time spent in the larval stage ranges from 13 to 18 days. Larvae possess a fecal fork and carry their feces over their body. This camouflage is thought to provide protection from predators and parasitoids. Pupation, which takes place on the host plant and under the fecal shield, lasts eight to 10 days. Females live an average of six months and lay about 1,500 eggs.
Chelymorpha cribraria has been recorded in the Neotropics from several species of Ipomoea, such as Ipomoea cairica (L.) Sweet. Per., Ipomoea cardiophylla Gray, and Ipomoea batatas (sweet potato). In Florida, it has been collected on various morning glories, but the only two that have been identified to species are Ipomoea indica (Burm. f.) Merr. and I. pes-capre (L.) R. Br., railroad vine. The two morning glories on Florida's list of endangered plants, Ipomoea microdactyla Griseb. and Ipomoea tensuissima Choisy (Coile 1994), occur in the areas where Chelymorpha cribraria is established.
I thank E.G. Riley, Texas A&M University, for his help in identifying Chelymorpha cribraria; Deborah L. Matthews and John Watts, University of Florida, for bringing the first specimen to my attention; Bonnie Coy, FDACS, for additional surveys; Roy Morris, Lakeland, for the specimen from Key Largo; and Jim Duquesnel, Florida Department of Environmental Protection, for finding the population of Chelymorpha cribraria at Cape Florida.
- Balsbaugh Jr. EU, Hays KL. 1972. The leaf beetles of Alabama (Coleoptera: Chrysomelidae). Auburn University, Agricultural Experiment Station Bulletin 441. 223 p.
- Blatchley WS. 1924. The Chrysomelidae of Florida. The Florida Entomologist 7: 33-39; 7: 49-57; 8: 1-7; 8: 17-23; 8: 39-46.
- Buzzi ZJ. 1988. Biology of Neotropical Cassidinae. pp. 559-580. In Jolivet P, Petipierre E, Hsiao TH (eds.). Biology of Chrysomelidae. Kluwer Academic Publishers, Dordrecht.
- Coile NC. 1994. Florida's endangered and threatened plants. Florida Department of Agriculture and Consumer Services, Bureau of Entomology, Nematology and Plant Pathology - Botany Contribution No. 29. 56 unnumbered p.
- Vasconcellos-Neto J. 1988. Genetics of Chelymorpha cribraria, Cassidinae: colour patterns and their ecological meanings. pp. 217-232. In P. Jolivet, E. Petitpierre, and T.H. Hsiao (eds.). Biology of Chrysomelidae. Kluwer Academic Publishers,Dordrecht.