Syritta pipiens (Linnaeus)
Syritta pipiens (Linnaeus, 1758).
Linnaeus, C. (1758) Systema naturae... Ed. 10, Vol. 1. 824 pp. L. Salvii, Holmiae [= Stockholm].
Ecology and Distribution
This species is becoming cosmopolitan; known from most of the Palaearctic, including North Africa, most of North America, South America and the Oriental region. But records from the Afrotropical region are apparently erroneous (Speight 2010).
In the Nearctic Region, Syritta pipiens is known from British Columbia to Newfoundland, south to California and Florida, and Mexico (Thompson 2010).
Adults' preferred environment: wetland; fen, edges of bogs and along the margin of almost any freshwater body, including lakes, ponds, ditches, canals, brooks and rivers; anthropophilic, occurring in most sorts of farmland, suburban gardens and urban parks (Speight 2010).
Flowers visited by adults: white umbellifers; Achillea, Allium, Aster, Calluna, Cardamine, Cirsium palustre, Convolvulus, Crataegus, Epilobium, Euphorbia, Galium, Jasione montana, Leontodon, Polygonum cuspidatum, Potentilla erecta, Prunus laurocerasus, Ranunculus, Rosa canina, Senecia jacobaea, Sorbus aucuparia, Tussilago (Speight 2010). See also the extended list in de Buck (1990).
The flight period for European specimens is from March to November, and in southern Europe probably all the year round, but most records are from May through October (Speight 2010).
Adults have low-flying, rarely more than 1 m. from the ground; settles on vegetation; males patrol stands of low-growing plants in bloom (see Parmenter 1956) (Speight 2010).
Larva of S. pipiens was described and figured by Heiss (1938) and Hartley (1961) and illustrated in colour by Rotheray (1994) and Bartsch et al (2009a); an inhabitant of various types of moist, decaying, vegetable matter, including cow dung and garden compost heaps (Speight 2010).
Larva (from Heiss 1938).
The immature stages of Syritta pipiens have been described in detail and figured by Metcalf (1916). The rectal gills, posterior spiracles, and cross section of the pharynx are figured by Kroger (1926) who gives an exhaustive morphological account of the larva. Hodson (1931) describes the larva and puparium of Syritta pipiens in comparison with those of Eumerus tuberculatus and figures the cephalopharyngeal skeleton, larva, and puparium of both. Johannsen (1935) describes again the larva and puparium of Syritta pipiens, using the descriptions of Metcalf and the figures of Metcalf and Kruger.
Length, 10 mm., width, 2.75 mm., height, 2 mm. The larva is broadly fusiform, tapering moderately toward the false head and more narrowly at the posterior end, and broadest from segments five to nine. The color is dirty yellowish and the entire body is covered with pale and delicate, close-set microscopic hairs, which are longer on the more exposed portions. The body bears, just anterior to the posterior respiratory process, three pairs of pointed fleshy projections.
The anterior segments are differentiated into a false head with about a dozen longitudinal furrows. The anterior spiracles are very dorsal in position, located between the first and second furrow from the midline and are sessile, each with apparently three rounded nodules on its summit. The head has a transverse band of microscopic hooklets above the mouth. There are seven pairs of prolegs; each proleg has about two dozen hooklets of varying sizes. On segments eleven and twelve are the conspicuous lateral processes, the anterior, shortest one on the eleventh, the middle and posterior ones, which are progressively longer, on the twelfth. They are covered with spinelets, which are longer toward the tip.
The posterior respiratory process is a brown, chitinized polished tube, about 0.75 mm. long. It is straight, tapering, and very slender, about five times as long as its width at the tip. The tubes are semitransparent, permitting the large tracheal trunks to be seen throughout its length. The posterior spiracular plates have centrally located circular plates and three pairs of contorted spiracles which are ornamented around the edge with from nine to fourteen lateral projections or denticles which are irregular in size and irregularly shaped. The plates are each surrounded by four tufts of feathered hairs.
According to Kruger (1926) the rectal gills are twelve-branched.
Recognition Characters. 1. Yellowish larvae about 10 mm. long with three pairs of posterior fleshy processes, the first shortest and the last longest. 2. Seven pairs of prolegs each with two dozen hooklets of varying sizes. 3. Shape of the aperture of the spiracles contorted and irregularly toothed with nine to fourteen denticles. 4. Slender, straight posterior process, tapering toward the tip and five times as long as wide at the top.
Puparium (from Heiss 1938).
Length, 6.8 mm., width, 2.95 mm., height, 2.68 mm. Elongate-ovate in outline, a little more attenuated posteriorly, nearly circular as seen from the front, a little flattened on the venter. Color yellowish white, darkening to dull muddy brown. The remnants of the three pairs of projections are still readily visible on the anal segments but the prolegs have disappeared and even the hooklets are difficult to find on the general roughened and soiled integument.
The pupal respiratory processes protrude from the upper half of the operculum as blunt, club-shaped projections. The enlarged distal half is studded with about 75 minute nodules in which are found the spiracular apertures. The posterior spiracular process is like that of the larva.
Food Habits.The stages of Syritta pipiens have been reported from cow and horse manure, from guinea pig manure and from human excrement. It has also been found in decayed and rotting tulip bulbs and in heaps of vegetable refuse (Hodson, 1931).