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Insects Confused with EAB Adults

June 6, 2007

Emerald ash borer adult.

Adult emerald ash borers (EAB) are expected to emerge and be present over the next 6 weeks. Although these insects are distinctive, with their -inch-long, bullet-shaped, metallic emerald green bodies, several insects are commonly confused with them.

Tiger beetle.
Tiger beetles are predators of insects, spiders, and other small animals. They are commonly found sitting on sidewalks and other open areas. The sixspotted green tiger beetle is about 1/2 inch long and bright metallic green, with small white spots on the wing covers. They actively fly in sunny conditions, always facing anyone nearby. Another species is about 3/4 inch long, a darker metallic green without spots. The light-colored larvae have large dark heads with huge jaws. The larvae lurk in holes in the soil, waiting for insects and other prey to pass by.

Ground beetles are predators of insects and other small animals, with the elongate larvae living in the soil and organic debris. Some specialize in feeding on snails. Many species are black with tan legs, but several are metallic green. The fiery searcher, Calasoma, is considerable longer and wider than the emerald ash borer, being about 1 inch long and 1/2 inch wide. The species that is metallic green was imported to control gypsy moths, as it climbs trees looking for caterpillars. As with other ground beetles, they are strongly attracted to lights at night, being commonly found in lighted parking lots in the morning. Another metallic emerald green ground beetle is about 1/2 inch long but with a considerable wider abdomen than emerald ash borer.

Sweat bee adult.
Sweat bees, also known as mining bees, live in soil, plant stems, or rotting wood, depending on the species. They raise their larvae in burrows on flower pollen and feed themselves on flower nectar. Thus, adults are important pollinators and are commonly seen on flower blossoms. Several species are metallic green, 3/8 to 1/2 inch long.

Cuckoo wasps, also known as cuckoo bees, are metallic blue to blue–green as adults. These 1/2-inch-long insects are commonly seen on flower blossoms. As with the sweat bees, they have the obviously separated body regions of head, thorax, and abdomen, as well as having clear, membranous wings. Even so, they are mistaken for emerald ash borers due to their metallic green color.

Bronze birch borers are in the same genus, Agrilus, as the emerald ash borer. These insects live as larvae in the cambium of declining birch trees, hastening their demise. Being closely related, the adults are the same size and shape as the emerald ash borer but, as the name indicates, are bronze-colored in sunlight rather than emerald green. In the shade, bronze birch borer adults appear blackish, whereas emerald ash borers are bright enough to appear green even in subdued light.

Honeylocust borers are also in the same genus as emerald ash borer. Its larvae are common in declining honey locust trees, feeding not only in the cambium but also tunneling deeper into the sapwood as well. The adults are the same size and shape as emerald ash borer but are black in color. The adults are commonly found on the foliage of honey locust when emerald ash borer adults are present.