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common name: clavate tortoise beetle
scientific name: Plagiometriona clavata (Fabricius) (Insecta: Coleoptera: Chrysomelidae)

Introduction - Synonymy - Distribution - Description - Hosts and Biology - Selected References

Introduction (Back to Top)

Plagiometriona clavata (Fabricius) is common and can be recognized easily by its general form and appearance.

Adult clavate tortoise beetle

Figure 1. Adult clavate tortoise beetle, Plagiometriona clavata (Fabricius). Photograph by David Cappaert, www.forestryimages.org.

The Integrated Taxonomic Information System lists two subspecies:

(ITIS 2010)

Synonymy (Back to Top)

Unfortunately, this relatively common beetle has gone under several names which created some confusion. The formal synonymy follows:

Plagiometriona clavata (Fabricius). Fattig 1948
Coptocycla clavata (Fabricius). Boheman 1855
Deloyala clavata (Fabricius). Dejean 1837
Cassida clavata Fabricius 1798

Some of the taxonomic confusion was discussed by Barber (1918, 1946) and Hincks (1952). Although there is no specific synonym listed, Barber (1918) suggested the possibility that Deloyala testudinaria from Central America may intergrade with clavata in Texas, New Mexico and Arizona.

Distribution (Back to Top)

The most extensive distribution records were provided by Barber (1918): Arizona, Florida, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Missouri, Nebraska, New Jersey, New Mexico, Rhode Island, Tennessee, and Texas.

Blatchley recorded it from Lake, Wells, Putnam, and Posey counties, Indiana (1918) and from Lake Worth, Enterprise, Eustis, and Gainesville, Florida (1924), suggesting that it is apparently confined to the northern half of the state.

Fattig (1948) recorded it from Atlanta, Georgia, Balsbaugh and Hays (1972) listed it from Lee, Madison, and Mobile counties, Alabama, and Wilcox (1954) reported it as common in Ohio.

Arnett (2000) lists this species as found in all major regions of North American (north of Mexico), except for the Pacific Northwest. However, this does not mean it is found in all the states or provinces in those regions.

Description (Back to Top)

Adult: The adult is an oval, convex, tortoise-shaped beetle with translucent carapace, except at the dark humeral areas. The length is 6.5 to 7.5 mm, while the width is 5.5 to 6.3 mm. Color varies from brilliant brassy green, golden and brown in life to a dull yellow brown to tan with dark markings in dead specimens. In side view, it is dome-shaped with a conical peak near the middle, behind the scutellum.

Adult clavate tortoise beetle

Figure 2. Adult clavate tortoise beetle, Plagiometriona clavata (Fabricius). Line represents 3 mm. Illustration by Division of Plant Industry.

Lateral view of an adult clavate tortoise beetle

Figure 3. Lateral view of an adult clavate tortoise beetle, Plagiometriona clavata (Fabricius), showing conical peak. Photograph by Division of Plant Industry.

The dorsal surface is rugose and tuberculate (no other species of United States tortoise beetle, subfamily Cassidinae, has such a surface). The antenna is variable in color, but at least some of the terminal segments are black; the segments are free when at rest, and there is no antennal groove on the underside of the prothorax; the third segment is slightly longer than the second segment. The head is covered by the arcuate front margin of the pronotum. The tarsal claws are angularly dilated at their base. [The illustration of this species by Dillon and Dillon (1961) has the legend reversed with that of Metriona bivittata (Say); Plagiometriona clavata is actually figure 9 on plate 74.]

Larva: The larva is a typical tortoise beetle type, but very unlike most other beetle larvae. The last abdominal segment has a special "fecal fork" which permits the attachment of dried fecal matter. This fecal mass is carried over the dorsum in the same form as trash bugs (Neuroptera), and presumably offers a degree of protection through camouflage. The body is green, flattened, and almost entirely fringed with whitish multispiculate projections.

Lateral view of the larva of a clavate tortoise beetle

Figure 4. Lateral view of the larva of a clavate tortoise beetle, Plagiometriona clavata (Fabricius). Head of larva is to the right. Anal fork with feces is held above larva. Photograph by Division of Plant Industry.

Posterior view of the larva of a clavate tortoise beetle

Figure 5. Posterior view of the larva of a clavate tortoise beetle, Plagiometriona clavata (Fabricius), showing last segment bearing the anal fork. Photograph by Division of Plant Industry.

Hosts and Biology (Back to Top)

Like many other members of the subfamily Cassidinae, this species appears to prefer plants of the family Solanaceae. Host records in the literature are mostly for adults and may not represent actual feeding: linden and oak (Blatchley 1910); sycamore, oak, linden, and Japanese lantern (Wilcox 1954); morning glory (Dillon and Dillon 1961); oak and various species of Solanaceae (Blatchley 1924).

Selected References (Back to Top)