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common name: giant water bugs, electric light bugs
scientific name: Lethocerus, Abedus, Belostoma (Insecta: Hemiptera: Belostomatidae)

Introduction - Life Cycle - Key to species of Florida Belostomatidae - Distribution - Selected References

Introduction (Back to Top)

The heteropteran family Belostomatidae contains the giant water bugs. These large, predatory, aquatic insects have the largest body size among the Heteroptera. Adults of some South American species reach 4 inches in length. Individuals occur in ponds and ditches where they suspend below the surface, respiring through two abdominal appendages which act as siphons. During mating season they fly from pond to pond or pool of water. It is during these flights that these insects fly to lights in large numbers, earning their other common name, "electric light bugs". Individuals are capable of inflicting a painful bite with their strong beak, and may also pinch with their front legs. Individuals prey on aquatic insects, small fish, frogs, tadpoles, small birds, and other organisms they are able to capture. Powerful enzymes are injected into prey to kill them. Adults of Lethocerus are considered a delicacy in Asia, and are eaten both fresh and cooked.

Dorsal view of an adult giant water bug, Lethocerus sp.

Figure 1. Dorsal view of an adult giant water bug, Lethocerus sp. Photograph by P. M. Choate, University of Florida.

Ventral view of the head of an adult Lethocerus sp., a giant water bug. showing the beak.

Figure 2. Ventral view of the head of an adult Lethocerus sp., a giant water bug. showing the beak. Photograph by P. M. Choate, University of Florida.

Life Cycle (Back to Top)

Eggs of Lethocerus are deposited above water on vegetation and other objects. Eggs of Abedus and Belostoma are glued onto males' backs by females. Egg carrying by males is a unique feature in these two genera. Curiously, Kraus (1985) reported that in the absence of sufficient size males, eggs will also be laid on backs of females. Eggs hatch in one to two weeks, with total development time ranging from one to two months. Adults may overwinter in the mud.

Giant water bug eggs, Lethocerus spp.

Figure 3. Giant water bug eggs, Lethocerus spp. Photograph by Lyle J. Buss, University of Florida.

Giant water bug nymph, Lethocerus spp.

Figure 4. Giant water bug nymph, Lethocerus spp. Photograph by Lyle J. Buss, University of Florida.

Key to species of Florida Belostomatidae (Back to Top)

Seven genera and approximately 60 species occur worldwide, with three genera and approximately 20 species found in North America. The following three genera containing eight species of Belostomatidae are known to occur in Florida (Henry and Froeschner 1988):

(species key modified from Bobb 1974, Pennak 1953)

1. Metasternum with a strong midventral keel, membrane of front wing reduced . . . . . Abedus immaculatus (Say)
1'. Metasternum without midventral keel, membrane of front wing not reduced . . . . . 2

2. Basal segment of beak longer than the second, less than 30 mm long (See Figure 5, below) . . . . . 3
2'. Basal segment of beak shorter than second, 35 mm or longer . . . . . 5

Dorsal view of an adult Abedus lutarium (Stål).

Figure 5. Dorsal view of an adult Abedus lutarium (Stål). Photograph by P. M. Choate, University of Florida.

3. Length 20 mm or greater in length; color dark; head variable; tylus variable . . . . . 4
3'. Length less than 20 mm; tylus not prominent; color pale brown or testaceous; head only slightly longer than front lobe of pronotum . . . . . Belostoma testaceum (Leidy)

4. Head slightly longer than frontal lobe of pronotum; tylus less convex, not prominent; claval commissure distinctly shorter than scutellum; form narrow, less tapering behind middle of hemelytra . . . . . Belostoma flumineum Say
4'. Head as long as middle of pronotum; tylus more convex, very prominent; claval commissure equal to or longer than scutellum; form broadly oval, strongly tapering behind middle of hemelytra . . . . . Belostoma lutarium (Stål)

5. Anterior femur with deep narrow groove for reception of the tibia . . . . . 6
5'. Anterior femur not grooved for reception of tibia . . . . . Lethocerus (Benacus) griseus (Say)

6. Middle and hind legs not banded, or only faintly so; interocular space equal to width of an eye; costal margins feebly but conspicuously curved . . . . . Lethocerus americanus (Leidy)
6'. Middle and hind legs distinctly banded (see Figure 6, below); interocular space not over three-fourths width of an eye; costal margin almost straight (see Figure 7, below) and subparallel . . . . . Lethocerus uhleri (Montandon)

Ventral view of an adult Lethocerus uhleri (Montandon). (Note banded middle and hind legs).

Figure 6. Ventral view of an adult Lethocerus uhleri (Montandon). (Note banded middle and hind legs). Photograph by P. M. Choate, University of Florida.

Dorsal view of an adult Lethocerus uhleri (Montandon).

Figure 7. Dorsal view of an adult Lethocerus uhleri (Montandon). Photograph by P. M. Choate, University of Florida.

Distribution (Back to Top)

Abedus immaculatus (Say) - Florida, Georgia, and Mississippi;
Belostoma flumineum Say - Quebec and New England, west to Manitoba and Colorado, southwest to Florida, Louisiana, and Arizona;
Belostoma lutarium (Stål) - Massachusetts southwest to Louisiana and Texas; Kansas;
Belstoma testaceum (Leidy) - New York west to Michigan and southwest to Florida and Texas;
Lethocerus griseus (Say) - Massachusetts west to Michigan; south to Florida and Texas; Mexico to Guatemala, West Indies;
Lethocerus uhleri (Montandon) - Massachusetts, west to Ontario, south to Texas; Mexico;
Lethocerus annulipes (Herrich-Schaeffer) - Florida? South America, West Indies; reported from Palm Beach, Florida.
Lethocerus americanus (Leidy) - Newfoundland, Maine to British Columbia, south to Utah and Nevada, Mexico, Florida?

Selected References (Back to Top)

Author: Paul M. Choate, University of Florida
Photographs: Paul M. Choate and Lyle J. Buss, University of Florida
Web Design: Kay Weigel
Publication Number: EENY-301
Publication Date: July 2003. Latest revision: October 2003. Reviewed: February 2019.

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Featured Creatures Editor and Coordinator: Dr. Elena Rhodes, University of Florida