DIPTERA. — SYRPHIDZE. 559 
lesia, Criorhina, and Xylota, the larvee of which live in the detritus 
of wood, as does also that of Chrysotoxum arcuatum, observed by 
Van Roser. That of Milesia vespiformis has been observed by 
Baumhauer ; it is thick, nearly oval, and of a reddish grey colour. 
The pupa of Criorhina apicata was discovered by Schrank; it is brown, 
convex above, flat beneath, the head furnished with two maxillary 
tumours, and the body terminated by a small tail. It closely re- 
sembles that of Xylota pigra, of which the exuvia alone has been 
observed, and which is also probably found in rotten wood. The 
pupa, or rather the puparium, of Xylota Florum, communicated to me 
by M. Van Roser, is short, and very much swollen, with two short 
appendages in front, the extremity of the body armed at the sides 
with short spines, and terminated by a short cylindrical tail (fig. 
1312)5.): 
The larva of Merodon clavipes was found by Réaumur (Mém. 
tom. iv. pl. 34.) and Van Roser in the bulbs of Narcissi, of which it 
devours the inside. It has the body (fig. 131.6.) whitish, thick, 
cylindrical, rather pointed at each end; the mouth is furnished with 
two scaly hooks, above which are two short bifid horns; the extremity 
of the body has two stigmata placed posteriorly upon a short foot- 
stalk, and two pointed tubercles; the real pupa is oval, with two 
anterior horns connected with two vesicles which communicate with 
the spiracles. Messrs. Serville and Saint Fargeau have confirmed 
these observations (Encycl. Méth. tom.x. p. 525.) ; Bouché has figured 
the larva and pupa of Merodon Narcissi (NVaturg. pl. 5. f. 7—11.). 
The pupa of Cheilosia ruficornis has been found at the root of a 
tree by Fallen, who has not, however, described it; and the larva of 
Syritta (Xylota) pipiens in horse-dung by De Geer; it is thicker in 
front than behind, with a small point on the head. That of Rhingia 
appears to reside in cow-dung, Réaumur having found a full-grown 
specimen in a vessel filled with that material. 
Van Roser found the larva of Milesia Oxyacanthe in the rejecta- 
menta of the river Neckar ( Verz. Wurtemb. Dipt. p. 10.); that of 
Brachyopa bicolor in the exuding sap of trees, and that of Syrphus 
scutellatus in rotten fungi. (Jdzd.) 
The larvee of Eristalis and Helophilus (fig. 131. 7. larva of H. tenax) 
differ materially from those of the rest of the family, not only in the 
situations in which they reside, but also in their structure, fitting them 
for their peculiar mode of life. It is in stagnant water and muddy 
