Description

Potentially Misidentified Species - No other flies of this genus are found in North America. This species would key out to Mosillus sp., an inland genus, in Wirth et al.'s (1987) key (Mathis 1988b).

Taxonomy

Kingdom	Phylum	Class	Order	Family	Genus
Animalia	Hexapoda	Insecta	Diptera	Ephydridae	Placopsidella

Synonyms

Gymnopa grandis; Placopsidella opaca; Placopsidella rossi

Invasion History

Chesapeake Bay Status

First Record	Population	Range	Introduction	Residency	Source Region	Native Region	Vectors
1987	Unknown	Unknown	Introduced	Regular Resident	Unknown-Marine	Western Pacific	Shipping(unspecified)

History of Spread

The shore fly Placopsidella grandis is known from tropical west Africa (Cameroon, Niger, Sierra Leone), from Asia (Japan and Taiwan), and Pacific islands including Belau and the Hawaiian Islands (Mathis 1986; Mathis and Zawartnicki 1995). Occurrences in Israel (1981), Panama (1967), and possibly Hawaii (1931), are probably due to human transport (Mathis 1986; Mathis 1988b). The Hawaiian specimens were on an introduced Australian plant (Atriplex semibaccata).

The first, and only detailed North American record (2 specimens) occurred in Kiptokeke VA (Northampton County), near Cape Charles in 1987 (Mathis 1988b). However, Mathis and Zawartnicki (1995) list a subsequent record in MD. Establishment of populations in the Chesapeake region is uncertain.

History References - Mathis 1986; Mathis 1988b; Mathis and Zawartnicki 1995

Invasion Comments

Residency - Flies of the genus Placopsidella breed in dead animal matter on marine strandlines (Mathis 1986). Larvae of many Ephydridae tolerate occasional or regular submersion, often by waters of high salinity (Simpson 1976).

Vector(s) of Introduction - The larvae and adults of this fly inhabit marine littoral zones where they are scavengers on cast up algae and animals. Thus, transport of flies with cargo or by other means on ships seems probable (Mathis 1988b). However, since this species has been collected from littoral plants (Mathis 1986; Mathis 1988b), transport with imported ornamental plants is also a possibility.

Ecology

Environmental Tolerances

	For Survival		For Reproduction
	Minimum	Maximum	Minimum	Maximum
Temperature (ºC)
Salinity (‰)
Oxygen
pH
	Salinity Range	poly-eu

Age and Growth

	Male	Female
Minimum Adult Size (mm)	2.7	2.7
Typical Adult Size (mm)	3.2	3.2
Maximum Adult Size (mm)	3.7	3.7
Maximum Longevity (yrs)
Typical Longevity (yrs

Reproduction

	Start	Peak	End
Reproductive Season
Typical Number of Young Per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproduction Event per Year
Reproductive Startegy
Egg/Seed Form

Impacts

Economic Impacts in Chesapeake Bay

Placopsidella grandis has no reported economic impacts in the Chesapeake region.

Economic Impacts Outside of Chesapeake Bay

Placopsidella grandis has no known economic impacts in its native or introduced range (Mathis 1988b). However, flies such as Placopsidella spp., while aesthetically unattractive on beaches, play a positive role from a human standpoint, in consuming stranded marine invertebrates (Simpson 1976).

References- Mathis 1988b; Simpson 1976

Ecological Impacts on Chesapeake Native Species

The establishment of Placopsidella grandis in North America and the Chesapeake Bay region may still be uncertain. This fly is probably too rare to have significant ecological impacts.

Ecological Impacts on Other Chesapeake Non-Native Species

Interactions of Placopsidella grandis with other introduced biota in the Chesapeake Bay region are unknown.

References

Kirk-Spriggs, A. H. (1986) The puparium of Placopsidella cynocephala (Diptera: Ephydridae) and notes on its biology, Mitteilungen der Schweizerischen Entomologischen Gesellschaft 59: 481-485

Mathis, Wayne N. (1986) Studies of Psilopinae (Diptera: Ephydridae), I: A revision of the shore fly genus Placopsidella Kertész, Smithsonian Contributions to Zoology 430: 1-30

Mathis, Wayne N. (1988) First record of the shore-fly genus Placopsidella Kertész from North America (Diptera: Ephydridae), Proceedings of the Entomological Society of Washington 90: 334-337

Mathis, Wayne N. (1989) A review of the beach flies of the Caribbean and Gulf of Mexico (Diptera: Canacidae), Proceedings of the Biological Society of Washington 102: 590-608

Mathis, Wayne N.; Zatwarnicki, Tadeusz (1995) World Catalog of Shore Flies, Memoirs on Entomology, International 4: 1-423

Simpson, Karl W. (1976) Marine Insects, In: (Eds.) . , Amsterdam. Pp. 465-495

Wirth, Willis W. (1987) Family Canacidae., 2 , Ottawa. Pp. 1079-1083

Wirth, Willis W.; Mathis, Wayne N.; Vockeroth, J. R. (1987) Family Ephydridae., 2 , Ottawa. Pp. 1027-1047

Placopsidella grandis

Invertebrates