Synanthedon acerrubri

Red Maple Clearwing Borer
Synanthedon acerrubri

POHL: 64-0087
MONA: 2546
GenBank: 687062

Identification:
Head: Head black, back of head (occiput) long orange hair. Nose cone (palpi) orange, underside and tip black. Inner margin of eye white.
Antenna: Black with white streak; long, reaching past mid-wing. Male has a short whitish to pale yellow streak just before tip and a row of scales (pectinate). Female has longer and brighter white streak.
Thorax: Black. Yellow streak running down each side of thorax. Underside yellow. Both the streaks and  underside become whitish with age.
Wings: Both front and hind wings are transparent, so the tiny dark mark on hindwing and hindwing margin may be visible through to the front wing.
Forewing margin black, streaked with some yellow on outer (costal) edge. Wide black bar at 2/3 wing length (discal cell). Male often has a yellowish streak in the margin below the bar; otherwise, this wing tip area is clear, not yellow. Wing tip area entirely bronzy-black. (A faint thin line may appear above the wing tip area; this is the outline of the hindwing.) Fringe short, grayish-black.
Hindwing margins narrow, black; outer (costal) margin streaked with yellow. Mid wing with a narrow black bar extending to first vein and which may be visible through front wing. Fringe grayish-black on outer edge, inner edge is yellow.
Legs: Top side of legs purplish-black. Underside yellow. Tips of shins (tibiae) and first 2 foot joints yellowish.
Abdomen: Black with yellow line on lower segment margin of 2, 4, 6 and 7, with 6 & 7 usually more orangish. Female banded or not. Male tuft ½ black in the middle, surrounded with orange. Female tuft orange.

Similar Species: Maple Callus Clearwing Borer Synanthedon acerni has wing tip area yellow with black veins and lacks any white on antenna.
Carmenta corni – Male abdomen tuft is mostly black, with some orange at center. Wing tip area is yellow. The orange at the back of the head extends to top of head, almost touching antenna base; on S. acerrubri top of head is entirely black, but may appear partly orange due to longer hairs at back of head flopping forward. C. corni feed on White-topped Asters Doellingeria umbellata and other plants and flies in July.

Size: 7 to 9 mm long. Wingspan 17 to 20 mm.

Habitat: Deciduous forests, parks, cities in street trees.

Food: Silver Maple Acer dasycarpum, Red Maple Acer rubrum, and Sugar Maple Acer saccharinum.  One report of Boxelder Acer negundo.

Flight Time: Late May to mid-August.

Life Cycle: The female lays up to 6 eggs in Maple twigs and branches up to 44 mm. (2 inches) diameter, unlike the Maple Callus Borer Synanthedon acerni which uses tree trunks. The female chooses damaged bark like the scars left from the Leopard Moth Zeuzera pyrina or beetles.
Larvae are 12 to 15 mm. White, thin with folded skin; head smooth, brown, mouth black. Feet pale yellow. Over-winters as larvae with continued feeding in the spring. Cocoon is thick and sticky, formed just under the bark. Pupa is capable of movement, it breaks through the bark so the moth can emerge.

Comments: Common in Ontario. Essex County.

For information on synonyms, references and type specimens see next page