Key to Common Insect Pests of Maple (Acer)


What is the nature of the problem?

Twigs and leaf petioles neatly cut off and strewn under tree answer: Continue...

Holes chewed in leaves answer: Continue...

Oval black and red bugs on flowers or seeds answer: BOXELDER BUG

Round or oval scales on twigs or limbs answer: Continue...

Clusters of soft-bodied gray or black insects on twigs and small branches answer: Continue...

Round or irregularly-shaped growths on leaves or petioles answer: Continue...

Twigs or Petioles Clipped

Fallen leaves with only half of petiole present answer: MAPLE PETIOLE BORER

Twigs of tender shoots wilted and turning black, small caterpillar in shoot answer: BOXELDER TWIG BORER

Woody twigs cut off squarely, borer hole on face of fallen twig answer: TWIG PRUNER

Young twigs with small hole with mass of extruded frass and silk, tip dieback answer: MAPLE SHOOT BORER

Holes Chewed in Leaves

Pale yellow-green caterpillar striped with darker green, pair of black horns near front end and black pegs along sides answer: GREENSTRIPED MAPLEWORM

Groups of hairy caterpillars with row of keyhole-shaped pale spots down back answer: FOREST TENT CATERPILLAR

Caterpillar with pairs of black and red tufts of long hairs at front and rear of the body and 4 tufts of shorter, whiter hair along back answer: WHITEMARKED TUSSOCK MOTH

Bright yellow caterpillars with 10 narrow black wavy lines along back, crawl with looping motion answer: LINDEN LOOPER

Caterpillars in spindle-shaped bags covered with bits of leaves answer: BAGWORMS

Round or Oval Scales

Gray-brown scales, shaped like oyster shells, on twigs answer: OYSTERSHELL SCALE

Flat, oval brown scale with cottony white mass protruding from underside answer: COTTONY MAPLE SCALE

Oval, convex, shiny brown scale answer: LECANIUM SCALE

White and dark brown soft scale answer: CALICO SCALE

Clusters of Soft-bodied Insects

Soft-bodied gray-brown insects along twigs or limbs answer: GIANT BARK APHID

Gray to black insects with fluffy wax on end of abdomen, usually on silver maple answer: WOOLLY ALDER APHID

Irregular Growths on Leaves

Irregularly shaped felt-like patches that may be red, green, or yellow answer: ERINEUM GALL

Small globular green, red, or black growths on upper surface of red maple or silver maple leaves, may be single or in clusters answer: MAPLE BLADDER GALL

Round yellow circle with red center and outer red ring answer: MAPLE EYESPOT GALL

1/4-inch long, thin growths extending from upper surface of sugar maple leaf answer: MAPLE SPINDLE GALL

Thickened swellings or purse-like growths on upper leaf surface along major veins answer: GOUTY VEIN GALL MIDGE


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