common oak moth

not listed

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SNR - Unranked

not listed

Common oak moth is a medium-sized, early season, graphic owlet moth. It occurs in the United States and southern Canada east of the Great Plains. Adults are found from March to May in woodlands and at forest edges.

Adults are 11⁄16″ to ⅞″ (18 to 23 mm) in length and have a wingspan of about 1½″ (38 mm). Moth size is sometimes given in terms of forewing length, which on this moth is ⅝″ to 11⁄16″ (17 to 18 mm).

The forewing background color is variable, from pale grayish-tan to brown. From the wing base to the tip there is a basal line, an antemedial (AM) line, a median line, a postmedial (PM) line, a subterminal (ST) line, and a terminal line. The AM line is a dark band bordered below with a thin pale line. The median line is a diffuse dark band. The PM line is pale and thin. The ST line is jagged, pale, and thin, but is often indistinct. The area between the PM and ST lines forms a dark band. The terminal line is represented by a row of dark spots between the veins. This may be the feature that gives the moth its species epithet atomaris, which means “with minute dots or points.” The kidney-shaped spot (reniform spot) in the rear half of the median area has a pale border above and is variably filled with dark scales. It sometimes appears as two separate spots.

The caterpillar is up to 19⁄16″ (4 cm) long, brown, and patterned with several pale to deep chocolate brown longitudinal stripes. The middle (middorsal) stripe is dark, bordered on each side by a wavy pale line that sometimes breaks the middorsal line into a row of diamond-shaped spots. A black stripe on each upper side (subdorsal) is broken into a series of irregular spots. On the sides of the abdomen there is a dark band that includes the breathing pores (spiracles). The leg-like structure (proleg) on the fourth abdominal segment (A4) is half as large as those on A5 and A6, and the proleg on A3 is half as large as the one on A4.

Total length: 11⁄16″ to ⅞″ (18 to 23 mm)

Wingspan: about 1½″ (38 mm)

Forewing length: ⅝″ to 11⁄16″ (17 to 18 mm)

Woodlands and forest edges

One generation per year: March to May

The larvae feed on leaves at night and are seldom seen.

Adults are active at night and will come to lights. The wings are held flat when at rest.

Oaks

Sources

4, 21, 24, 29, 30, 75, 82, 83.

Location: Great River Bluff State Park