. Fig. 126. Wing of Ps. formicarum (J. Female. Quite similar; the ovipositor pointed, black and shining; the hairs at the hind margin of sixth segment conspicuous. Length 0,7 to fully 1 mm. Ps. formicarum does not seem to be common in Denmark, but this is probably only because it has not been saught for in the right way; I have only taken it on Bogo south of Sealand on ^"/t—Vs 1917; I took it here with the net in grass in a garden, and it was present somewhat numerously; I have also seen a specimen in Lyngby Mose on ^Ve 1918. I have, however, never searched for it at the nests of Lasiiis
. Fig. 126. Wing of Ps. formicarum (J. Female. Quite similar; the ovipositor pointed, black and shining; the hairs at the hind margin of sixth segment conspicuous. Length 0,7 to fully 1 mm. Ps. formicarum does not seem to be common in Denmark, but this is probably only because it has not been saught for in the right way; I have only taken it on Bogo south of Sealand on ^"/t—Vs 1917; I took it here with the net in grass in a garden, and it was present somewhat numerously; I have also seen a specimen in Lyngby Mose on ^Ve 1918. I have, however, never searched for it at the nests of Lasiiis niger', it is known to be parasitic on this ant; Wasmann men- tions (Biol. Zentralbl. 38, 1918, 317) that when in summer material from the nest of the said ant is spread out, the females of the Phorid occur numerously, hovering over the worker-ants, rushing down on them to sting them between the abdominal segments and here laying the egg. Donisthorpe has mentioned that the species also chases Lasiiis flaviis, umbratus, fidiginosus, Formica sanguinea^ Tapinoma erraticum and Myrmica lobicornis, but Wasmann gives good reasons for the opinion that its normal host is Lasiiis Jiiger^ and this author gives 1. c. upon the whole an interesting account of its biology to which I refer. My specimens seem to be darker than those originally described, they have the legs yellowish to nearly brownish yellow, and the halteres blackish or brownish, while Verrall described both legs and halteres as pale yellow, and so also Strobl; a Dutch specimen from Pater Schmitz is, however, similar in colour to my specimens. Geographical distribution: — Besides from Denmark known from Britain, Holland and down into Styria, and it is probably widely distributed.
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Keywords: ., bookauthorlu, bookcentury1900, bookdecade1900, booksubjectdiptera
