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locust borer

(Megacyllene robiniae)

Information
Photos
Slideshows
Videos
Sightings

Conservation • Description • Habitat • Biology • Distribution • Taxonomy

Conservation Status

Photo by Alfredo Colon

IUCN Red List

not listed

NatureServe

NNR - Unranked

Minnesota

not listed


	Description
	Locust borer is a large, colorful, round-necked longhorn beetle. It is native to the Appalachian and Ozark regions of the eastern United States, where its larval host, black locust, is also native. Black locust has been widely cultivated as an ornamental and as a soil improver in restorations. As the tree spread across North America, locust borer went with it. Locust borer is now common in Minnesota. Larvae develop within the stems of their host and are rarely seen. Adults are seen during the day from August to October on goldenrods. It is considered a serious pest of black locust. The wood of infected trees is commercially worthless, and the infected trees may die. Adults are 7⁄16″ to 1⅛″ (11 to 28 mm) long and are densely covered with short, velvety hairs. They are jet black with numerous bright yellow bands and spots, looking something like a wasp or hornet. This is probably an example of Batesian mimicry, making the beetle appear unpalatable to potential predators. The body is constricted between the thorax and the abdomen, forming a distinct rounded “neck”. The head is black with three yellow bands. The face is slanted forward, not vertical. The small antennae-like structures (palpi) emerging from the lower jaws (maxillae) are blunt at the tip, not pointed. The antennae are long, at least half as long as the body. The base of each antenna is surrounded by the compound eye. The exoskeletal plate covering the thorax (pronotum) is black, rounded, and widest near the middle when viewed from above, strongly convex when viewed from the side. It is black with yellow front, rear, and lateral margins, and two narrow yellow bands. The hardened forewings (elytra) are black with seven narrow yellow bands. The third band is strongly W-shaped. The inner one-third of each elytron is abruptly depressed. The legs are reddish.

	Size
	Total length: 7⁄16″ to 1⅛″ (11 to 28 mm)

	Similar Species
	Painted hickory borer (Megacyllene caryae) appears nearly identical but the adult emerges in the spring. It has not been recorded in Minnesota.


	Habitat
	Wherever black locust has been planted


	Biology
	Season
	August to October

	Behavior
	Adults are active during the day

	Life Cycle


	Larva Food
	Black locust

	Adult Food
	Goldenrod flower pollen


	Distribution
			Sources 24, 27, 29, 30, 82.
	9/*6/2023

	Occurrence
	Common


	Taxonomy
	Order	Coleoptera (beetles)
	Suborder	Polyphaga (water, rove, scarab, long-horned, leaf, and snout beetles)
	Infraorder	Cucujiformia
	Superfamily	Chrysomeloidea (longhorn beetles and allies)
	Family	Cerambycidae (longhorn beetles)
	Subfamily	Cerambycinae (round-necked longhorn beetles)
	Tribe	Clytini
	Genus	Megacyllene

	Synonyms
	Megacyllene flexuosum Megacyllene pictus

	Common Names
	locust borer

Glossary

Elytra

The hardened or leathery forewings of beetles used to protect the fragile hindwings, which are used for flying. Singular: elytron.

Maxillae

Paired mouth structures of arthropods located immediately behind the mandible and used for tasting and manipulating food. “Under-jaws”.

Palp

Short for pedipalp. A segmented, finger-like process of an arthropod; one is attached to each maxilla and two are attached to the labium. They function as sense organs in spiders and insects, and as weapons in scorpions. Plural: palpi or palps.

Pronotum

The exoskeletal plate on the upper side of the first segment of the thorax of an insect.


	Visitor Photos

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	Alfredo Colon














	Greg Watson





	MinnesotaSeasons.com Photos

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	Slideshows


	Locust Borer Andree Reno Sanborn

	About Megacyllene robiniae

slideshow


	Visitor Videos

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	Other Videos


	Locust borer beetle eating pollen in flowers GoTrails

	About Oct 6, 2019 Locust borer beetle crawling / walking and eating / feeding on pollen / nectar of bright yellow flowers of goldenrod plants \| Bee-like, Wasp-like \| Megacyllene robiniae, Robinia borulo, cyllène du robinier \| Coleoptera, Käfer, coleópteros, escarabajos, coléoptères, coleotteri \| serious pest of the black locust tree \| Wildlife, Animal Behavior, Nature, Insect facts \| #GoTrails, #beetle, #arthropod, #insect, #insects, #beetles, #animalforkids \| HD video, nature sounds



	Longhorned Beetle Wasp Mimic - Locust borer Stoil Ivanov

	About Sep 1, 2019 Locust borer ( Megacyllene robiniae ) Filmed on 8-31-2019 McDonald Woods Forest Preserve ,Lindenhurst Illinois. Good example of Batesian mimicry. Pest of the Black locust tree , but so beautiful.



	Locust Borer, Part 1 - August 25, 2013 Don Gagnon

	About Aug 26, 2013 Locust Borer (Megacyllene robiniae), Pottersville Woods, Somerset, Massachusetts, Sunday morning, August 25, 2013, 12:57 PM - Canon PowerShot SX50 HS MVI_43272; 1:11 min.

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Visitor Sightings

Report a sighting of this insect.
		This button not working for you? Simply email us at info@MinnesotaSeasons.com. Be sure to include a location.



Alfredo Colon 8/25/2022	Location: Albany, NY



Alfredo Colon 8/16/2022	Location: Albany, NY



Alfredo Colon 8/11/2022	Location: Albany, NY



Greg Watson 9/23/2021	Location: Apple Blossom Overlook, near La Crescent, Winona County MN



Alfredo Colon 8/31/2019	Location: Maplewood Nature Center



MinnesotaSeasons.com Sightings