Shore flies (family Ephydridae) are common insects, usually tiny and drab, that live near any kind of water. As with many insect groups, if you look closer, you will discover that some of them come in interesting forms and have amazing modes of life. Probably the most distinctive shore flies belong to the genus Ochthera, which have huge, mantis-like forelegs which they use to capture insect prey (Fig. 1; and see video below). O. tuberculata is the only common and widespread species of Ochthera in North Carolina, and can be collected throughout the year near ponds and streams. The NCSU collection has 47 specimens, mostly from Raleigh. It’s always exciting to find Ochthera, and this last November I collected several of them very near to the NCSU campus.

Because of its distinctive appearance, the genus Ochthera was recognized very early, in 1802 by Latreille, and a member of this genus was in fact the first ephydrid species described (1776, as Musca mantis). O. tuberculata was described by Loew in 1862. Loew described on the next page O. rapax, which Clausen (1977) found to be a synonym (the same species). O. tuberculata was considered by Sturtevant and Wheeler (1954) as a subspecies of a widespread Ochthera mantis, which is now known to be a complex of several closely related species. Clausen (1977) revised the genus Ochthera and confirmed O. tuberculata as a valid species separate from O. mantis.

Ochthera tuberculata can be distinguished from other North American Ochthera species by the reddish-orange tarsi; other species have darker brown to black tarsi. Also, O. tuberculata has only one “inner flexor seta”, while other species have two or more of these setae in a row along the inner (antero-ventral) edge of the modified femur. Like species of the O. mantis complex, O. tuberculata lacks the facial markings and prothoracic tarsal modifications of some other Ochthera species. Size also varies among Ochthera species. O. tuberculata is usually between 3.8 and 4.5 mm; members of the O. mantis complex are usually larger, while some other species are smaller. (see Clausen, 1977)

Ochthera is one of only a few predaceous Ephydrids – most others feed on algae and detritus (Foote, 1995). Various aspects of Ochthera biology have been recorded (see Clausen, 1977), and Simpson (1974) reported specifically on O. tuberculata and two related species. From what he reported, O. tuberculata and O. mantis (s.lat.) appear to have very similar biologies. Adult Ochthera are probably generalist predators – they have been observed capturing and feeding on various flies, including mosquitoes and midges, as well as leafhoppers, planthoppers, and other insects. Deonier (1972) also observed adults feeding on midge larvae, which they fished from the mud with their forelegs. Larvae of Ochthera, presumably including O. tuberculata, feed on midge and mosquito larvae, which they consume by wrapping around them, then piercing to feed on internal tissues (Simpson, 1975).

Ochthera tuberculata is found in a variety of wetland habitats, but appears to be most common on muddy or sandy shores of ponds or streams (Clausen, 1977). Like most ephydrids, larvae are aquatic to semi-aquatic and are found in or on the substrate in shallow, shoreline areas (Simpson, 1975).

Widespread throughout the Atlantic Coastal Plain, from Massachusetts to Florida, and along the Gulf Coast to Texas. Clausen (1977) notes a few records from Midwestern states (Illinois, Missouri, and Wisconsin).

• Clausen, P.J. 1977. A Revision of the Nearctic, Neotropical, and Palearctic Species of the Genus Ochthera, including one Ethiopian species, and one new species from India: A bicentennial revision (two hundred years of Ochthera). Transactions of the American Entomological Society 103(3): 451-530. (link)

• Deonier, D.L. 1972. Observations on mating, oviposition, and food habits of certain shore flies (Diptera:Ephydridae). Ohio Jour. Sci. 72(l):22-29. (link)

• Foote, B.A. 1995. Biology of shore flies. Annual Review of Entomology 40: 417-442. (link)

• Simpson, K.W. 1975. Biology and immature stages of three species of nearctic Ochthera (Diptera: Ephydridae). Proceedings of the Entomological Society of Washington 77(1): 129-155. (link)

• Sturtevant, A.H. and M R. Wheeler. 1954. Synopses of nearctic Ephydridae (Diptera). Transactions of the American Entomological Society 79:151-261.