426 Phoridae. 



events, not to be described, but it is well known that the species are 

 parasitic on ants. The European species has Lasius niger as its normal 

 host, but has also been observed by some other species of ants, as 

 mentioned below under this species. The other six species of the 

 genus (which I take as well distinguished from Plastophora, see 

 Schmitz, Zool. Mededeel. 'sRijks Mus. Leiden, II, 30) occur in the 

 West Indies and North and South America, and of them all or almost 

 all it is known that they are parasitic on Solenopsis geminata, behaving 

 in a similar way as the European species. (It has also been suggested 

 for Ps. solenopsidis, which was observed to chase only ants marching 

 witli prey, that the Phorid tried to oviposite in the prey, see Schmitz, 

 Deutsch. Ent. Zeitschr. 1915, 502). 



To the genus only one European species belongs, also occurring 

 in Denmark. 



1. Ps. formicarum Verrall. 



1877. Verr. Journ. Linn. Soc. London, XIII, 258 {Phom). — 1908. Wood, 

 Ent. Month. Mag. 2, XIX, 168, 174, fig. {Phora). — 1910. Kertész, Cat. Dipt. 

 VII, 415 {Plastophora). — 1914. Brues, Bull. Wisc. Nat. Hist. Soc. XII, 137 

 (Plastophora). — 1918. Sclimitz, Jaarb. Natuurh. Genootsch. Limburg 1917, 124. 



Male. Frons a little broader than high, greyish black, dull; 

 antennæ brownish or blackish brown, third joint oval; arista apical, 

 short and straight, apparently bare. Palpi 

 yellow, with ordinary bristles on the outer part. 

 Thorax blackish, dull, with brownish pube- 

 scence and one pair of dorsocentral bristles. 

 Scutellum with four bristles, the outer smaller 

 than the inner. Pleura brownish. Abdomen 

 short, black and dull, very sparingly liaired. 



^. ,^, ^ „ Hypopygium small; anal tube long, yellow, 



Fig. 125. Frons of . . ,:^ , , ' , , , . 



Ps formicarum f? ^* ^^ ^^^ ^^ *"^ base, but much broadened out- 



wards and thus high near the apex, and it is 



strongly compressed with the pair of apical hairs distinct and some- 



what large. Legs somewhat robust, front tarsi with the joints short, 



the fifth being the longest; hind femora a little dilated and also hind 



tibiæ, especially outwards; the legs are yellow or yellowish, hind femora 



with some sparse, somewhat strong anteroventral hairs below the 



apical half; hind tibiæ with the posterodorsal row of hairs small. 



Wings a little yellowish, veins brownish or pale brownish; costa 



