Eristalis. 413 



The pupa stage lasts from nine to twenty days or more according to 

 the weather. Reaumur (1. c. 472) has a curious observation ; he savs 

 that he saw a pupa in which the imago was ready to creep out, the 

 imago had the posterior end forwards and must thus have turned 

 round in the puparium, and the author thinks that this is the normal 

 method for these flies and that they split the puparium with the 

 posterior end; Miall thinks thas this observation need be con- 

 firmed before accepted; Réaumur's observation must, of course, be 

 due to some mistake, the imago^ as I have often asserted myself, has 

 the head forwards when ready to creep out and comes out with the 

 head first. — The eggs are deposited a little above the surface of the 

 water ; Reaumur saw the females of several species deposit their eggs 

 on the sides of buckets with water in his garden; the eggs are white, 

 oblong, fmely chagreened. Zetterstedt (1. c. II, 660) notes that he has 

 seen females of E. arhustorum laying eggs in the mud at horders of 

 stagnant waters, and he tells (1. c. 666) that he once saw several 

 females of E. anthophorinus around a carcass of a sheep lying in water, 

 sometimes setting down on it, he thinks to deposit the eggs. I pos- 

 sess a leaf of Sparganium with a heap of about half a hundred 

 eggs of some Eristalin, taken on '"h. 



Most or all species have no doubt more than one brood in the 

 year, and, as mentioned above, I have seen larvæ and pupæ at very 

 different times of the season; there is thus evidently no regularity in 

 the time of development. With regard to hibernation the species 

 hibernate, I think, in every stage of the larva and also as pupa; I 

 once took on ^Vs in a ditch a great number of larvæ in all sizes 

 from quite small to fuU grown, and also pupæ; if the winter is hard 

 the larvæ perish quite or partly. Verrall suggests that E. pertinax 

 may hibernate also as imago and this may be possible for this as 

 well as perhaps also for other species. 



The species of Eristalis are beautiful flies, especially the velvet 

 pilose species; they occur generally near water where they also 

 deposite their eggs, some occur especially at the shore, and they 

 frequent many various flowers, especially Gompositæ and Umbelliferæ ; 

 most or all species are seen during the whole season from early spring 

 to late autumn. 



Of the genus about 35 species are recorded from the palæarctic 

 region, but of these only about 25 are European; 15 have been found 

 in Denmark. 



The genus has been divided into several subgenera by Rondani 

 and Mik, according to the hairiness of the arista, the eyes in the male 

 being touching or separated, and the colour of the eyes, but the sub- 



