Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

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Belostomatidae of Michigan - Electric Light Bugs - Identification


Attracted to lights at night, the large bugs are also often called "electric light bugs." Adults overwinter in streams and rivers, often along undercut banks and underneath large woody debris, then disperse in spring to lentic habitats where they often hide among vegetation and woody debris. Belostomatids are predaceous, grasping prey with their strong forelegs and using piercing-sucking mouthparts to inject an anesthetic and digestive salva into their prey (insects - including members of their own species, larval amphibians and small fish), then sucking up their prey's fluids. Like notonectids and naucorids, these animals can deliver a very painful bite when handled. Adults overwinter, and mating and egg-laying occurs in late spring or early summer. Unusual among insects, species of Belostoma and Abedus have male parental care, where females attach eggs to the male's back who then guards and hydrates the eggs until they hatch. This is thought to have arisen through a male "strategy" of assuring parentage (counter sperm competition).

There are two species of Lethocerus, one species of Benacus, and two species of Belostoma recorded from Michigan, with Lethocerus americanus and Belostoma flumineum by far the most common in our state. Species of these genera are widespread in southern Canada southward towards Central America and West Indies (Lethocerus) and into much of South America (Belostoma). (A fourth genus, Abedus, is found in the southern and southwestern USA southward into Central America). Benacus, placed as a subgenus of Lethocerus by Laucke and Menke (1961), was recently elevated (rather re-elevated) to genus (Goodwyn 2006).

Adults are recognized by having well-developed wings, the basal half of the forewing being hardened, leathery.

Adults (adapted from Menke 1979 and Hilsenhoff 1984)

    1a a. Total body length > 40 mm Lethocerus and Benacus, 2
    b. Metatibiae and metatarsus thin, flattened, much broader than the middle tibiae and tarsi
    c. Abdominal sternites divided longitudinally by a suturelike fold into median and parsternites
    d. Length of basal segment of beak about 0.5x that of the second segment
    1b a. Total body length < 26 mm Belostoma, 4
    b. Tibia and tarsus of middle and hindleg similar
    c. Basal segment of beak about equal to segment segment
    2a(1a) a. Closing face of fore femur without a groove Benacus griseus (Say)
    also: Outer margin of hind tibia broadly curved; width of hind tarsal segment 1 greater than least interocular distance
    2b a. Closing face of fore femur with a groove 3
    also: Outer margin of hind tibia nearly straight; width of hind tarsal segment 1 less than, or equal to, least interocular distance
    3a(2b) a. Appressed pubescence (dense lawn of tiny matted hairs) of ventral laterotergite 1 extending to epimeron Lethocerus americanus (Leidy)
    b. Disk of mesosternum covered with short hairs and uniformly tumid
    3b a. Appressed pubescence covering only 1/2-2/3 the length of ventral laterotergite 1, not attaining to the epimeron Lethocerus uhleri (Montandon)
    b. Disk of mesosternum covered with minute spinues, and frequently with two parallel bulges
    also: Abdominal venter uniformly yellowish with scattered brown flecks
    4a(1b) a. Ventral paratergite 2 (first visible lateral abdominal sternite) glaborous Belostoma lutarium (Stål)
    b. Appressed pubescence of ventral paratergites 4-7 separated from middle sternites by a narrow strip devoid of setae
    c. Scutellum about as long as hemlytral commisure
    d. Lateral margin of pronotum nearly straight in outline
    4b a. Ventral laterotergite 2 with appressed pubescence of ventral laterotergites extending to mesal edge of lateral abdominal sternites, and extending onto mesal sternites Belostoma flumineum Say
    b. Appressed pubescence of ventral paratergites 4-7 extending to mesal edge of lateral abdominal sternites, and extending onto mesal sternites
    c. Scutellum distinctly longer than hemelytral commisure
    d. Lateral margin of pronotum usually concave in outline

Nymphs (based on Menke 1979)

    1a Protarsus with two equally developed claws Lethocerus and Benacus
    1b Protarsus with one long claw Belostoma


    Perez Goodwyn PJ. 2006. Taxonomic revision of the subfamily Lethocerinae Lauck & Menke (Heteroptera: Belostomatidae). Stuttgarter Beiträge zur Naturkunde Serie A (Biologie) 695:1-71.
    Hilsenhoff WL. 1984. Aquatic Hemiptera of Wisconsin. The Great Lakes Entomologist 17(1):29-50.
    Menke AS. 1979. Family Belostomatidae, pp. 76-86 in Menke AS (editor), The semiaquatic and aquatic Hemiptera of California. Bulletin of the California Insect Survey 21:1-166 + xi.

Page created: June 13, 2003; Last edited: November 06, 2013 (EB)