Diagnosis. Usually small (2.5-6.0 mm) flies without bristles. Head relatively small, eyes holoptic in both sexes. Antenna 3-segmented. Thorax often humpbacked. R2 unbranched or absent, calypter well-developed, often arched. Empodia pulvilliform. Abdomen usually globose.
Biology. Larvae are obligatory internal parasitoids of spiders, showing hypermetamorphosis. The first instar larva actively searches for its host. Usually there is a single parasitoid per host. At completion of its development, the larva leaves the host and pupates in a web the spider has built just prior to its death. There are apparently no fixed host-parasitoid relationship at species-level. Adult flies appear to be rare, but mass aggregations have been reported. Flies usually sit on the vegetation or objects in the landscape. Aerial swarms were reported for several species.
References to the local fauna. Van Aartsen (1997), Van der Goot (1963), H. de Jong et al. (2000), Van der Leij (1999), Theowald (1954a).
How to quote this page: Jong, H. de, & Th. Zeegers, 2001. Family Acroceridae. In: Beuk, P.L.Th. (Ed.): Checklist of the Diptera of the Netherlands, https://diptera-info.nl/news.php?fam=Acroceridae (date accessed: 03/01/2025).
NL: 7
B: 4
D: 7
UK: 3
World: 520
ACROCERIDAE
= CYRTIDAE
Acrocera Meigen, 1803
sanguinea Meigen, 1804
N; added as trigramma by Van Aartsen (1997: 7)
Note 1
= trigramma Loew, 1845
Ogcodes Latreille, 1796
= Oncodes Meigen, 1822: emend.
fumatus Erichson, 1846
N; added by H. de Jong et al. (2000: 176)
gibbosus (Linnaeus, 1758)
N
reginae Trojan, 1956
N; added as varius by Theowald (1954a: 30)
Note 2
= varius Latreille in Olivier, 1812: misident.
varius Latreille in Olivier, 1812
N; added by H. de Jong et al. (2000: 177)
zonatus Erichson, 1840
N
Paracrocera Mik, 1886
orbicula (Fabricius, 1787)
N; added as manevali by Van Aartsen (1997: 7)
Note 3
= borealis (Zetterstedt, 1838)
= manevali Séguy, 1926: misident.
Note 4
Notes
Note 1
Again added by H. de Jong et al. (2000: 175). Acrocera trigramma was synonymised with A. sanguinea by H. de Jong (2001: 187).
Note 2
Misidentification pointed out by H. de Jong et al. (2000: 178).
Note 3
Misidentification pointed out by H. de Jong et al. (2000: 178). Spelling of orbiculus in H. de Jong & Zeegers (2002) corrected to orbicula.
Note 4
Though listed as misidentification, the status of P. manevali is still unclear. It may well be a synonym of P. orbiculus.