unknown leaf beetle

not listed

not listed

not listed

Unknown leaf beetle is a medium-sized calligrapher beetle. It occurs in the United States from Maine to Connecticut, west to Minnesota and Ohio, and south along the Appalachian Mountains to northern South Carolina and Tennessee. It also occurs in southern Canada from Nova Scotia to Manitoba. Adults are found from April to September in deciduous and mixed forests and woodlands. Both adults and larvae feed on the leaves of birch trees.

Adults are 5⁄16″ to ⅜″ (7.5 to 9.5 mm) in length. The body is elongated-oval when viewed from above and very convex when viewed from the side. It is mostly creamy white with dark markings. The head, exoskeletal plate covering the first segment of the thorax (pronotum), and dark markings on the hardened wing covers (elytra) are black with a metallic green sheen (dark).

The head is dark and is usually partially visible when viewed from above, but it can be withdrawn into the body. The antennae are short, less than half as long as the body. They are slender and have 11 segments. They are weakly expanded (clubbed) beyond the fifth segment, gradually enlarged as they approach the tip. The eyes are not notched.

The pronotum is dark and unmarked. It is three times wider than long, nearly as wide as the base of the elytra. The small triangular plate between the bases of the elytra (scutellum) is dark.

The elytra are creamy white with 3 dark stripes and 10 or more isolated dark spots. The markings are variable, and they have been named as an aid to identification of the species in this genus. The stripes include: a complete stripe on the inner margin (sutural stripe); a complete stripe near the inner margin (subsutural stripe); and a short, curved stripe (arcuate stripe). The arcuate stripe has a front (basal) lobe and a rear (apical) lobe. The spots include: a boot-shaped spot near the base in the shoulder area (humeral spot); a spot near the outer margin at the halfway point (midlateral spot), a spot near the rear on the downward slope of the elytron (spot of apical declivity); and a spot near the tip (apical spot). The subsutural stripe merges with the sutural stripe. When the arcuate band is divided into two separate spots, the subsutural stripe merges usually with the basal spot, sometimes with the top spot, sometimes with both. The midlateral spot is present. The turned under lateral edge of each elytron (epipleuron) is blackish with a metallic sheen.

The legs are brownish-orange. The last part of each leg (tarsus), corresponding to the foot, has five segments. The fourth segment is very short and is concealed within the broadened tip of the third segment, making the tarsus appear to have only four segments. There is a pair of claws at the tip of the tarsus on each leg. The claws are well separated at the base.

Total length: 5⁄16″ to ⅜″ (7.5 to 9.5 mm)

This is the only species in the Calligrapha scalaris group that has black epipleura and that feeds on birch. Hop-hornbeam leaf beetle (Calligrapha ostryae) has brown epipleura and feeds on hop-hornbeam. It does not occur in Minnesota. All other species in the group have pale epipleura.

Deciduous and mixed forests and woodlands

April to September

Adults chew holes in leaves. Larvae consume the entire leaf except for the veins.

Leaves of birch trees

Leaves of birch trees

Sources

24, 29, 30, 82, 83.

Calligrapha ignota is much more common than this map, and distribution maps from other sources, would suggest. Many sightings, including specimens in museum collections, are believed to be misidentified as Calligrapha scalaris.

Tribe
Some sources place the genus Calligrapha in the tribe Chrysomelini, others sources place it in the tribe Doryphorini.

Species group
The species Calligrapha scalaris was first described by John Eatton LeConte in 1824 on the basis of color and two conspicuous markings on the wing covers (elytra): a moon-shaped marking in the shoulder (humeral) area; and a broad, tooth-like marking connected to the middle (sutural) stripe. The beetle was reported to be an occasional serious pest of American elm. LeConte’s description accurately distinguished the new species from all other Calligrapha species then known. Since then, at least thirteen new species have been described that share these characters.

In 1945, W. J. Brown identified a species complex of several species that were morphologically very similar but had very different host preferences and ecologies. A more recent study (Gómez-Zurita J., 2015) analyzed the original material from the Calligrapha scalaris collections of LeConte (1824) and of G. H. Horn (1884). The author found the collections contained as many as nine distinct species, many having no association with elm. He redefined the original species and defined fourteen species as the “Calligrapha scalaris” group.

… found on my deck railing.

Location: Lake Shore

… found on my deck railing.