315 
this country, as well as in our neighbouring countries, 
also in Belgium, France, England and Russia. It is a pa- 
rasite on the eggs of water insects which are laid on or 
in waterplants or on stones; it occurs both in still and 
running water. Ås hosts can be named: eggs of Aphelo- 
cheirus (Hj. Ussing), eggs of Ranatra, Dytiscus, Pelobius, 
Agabus, Dragon flies, Notonecta, and Erythromma najas 
(Kaj L. Henriksen). It can be caught in the water, but 
the easiest manner is to bring the water plants home on 
which the host eggs are laid, and breed it. 
The wingless and subapterous females appear to be 
the most common while males and winged females are 
rare. 
Length: 0.5—1.3 mm. 
Europe, also in Denmark. 
Specimens in Zoological Museum, Copenhagen. 
For further information as to the biology of this spe- 
cies, the reader is referred to a preceding article in this 
volume upon Aquatic Hymenoptera by Kaj L. Henriksen 
(p- p. 168 —178). 
Oligosita Haliday. 
1851. Oligosita. Haliday (Walker) Ann. & Mag. Nat. Hist. (2) VII 
p. 212 O. 
1879. = Westwood. Trans. Linn. Soc. London. Zool. (2) I. p. 
591. 
1897. — Aurivillius. Ent. Tidsskrift. p. 251. 
1898. = Dalla Torre. Cat. Hym. V. p. 5. 
1904. _ Ashmead. Classification. p. 360. 
1904. Westwoodella. Ashmead Classification. p. 559 — 360. 
1907. Oligosita. Schmiedeknecht. Hymenopt. Mitteleuropas p. 491. 
1909. Westwoodella. Schmiedeknecht. Gen. Insect Fasc. 97 p. 550. 
1909. Oligosita. Schmiedeknecht. Genera Insectorum. Fasc. 97. p. 550. 
1914. ~ Girault. Mitt. a. d. Zool. Mus. Berlin. VII B. 2 H. p. 
148. 
1915. — Wolff. Zeitschr. f. Forst- u. Jagdw. XLVII p. 563. 
This genus was originated by Haliday, and Walker 
reproduces the description of the first species from Hali- 
days manuscript in the work quoted above. Strangely 
