320 



it certainly does not do so unless there is an injury, and then it feeds, 

 not upon the wood but upon the exuding sap and attendant fungus. 

 The genus is of interest, however, because it is an exception to the 

 general rule in Mycctopliilidcr in respect to its respiratory system. A 

 description of the larva and pupa of a species of Sciara is given herein 

 which serves to show the differences between the peripneustic and 

 amphipneustic types of larvae. 



SCIARID.^ 

 Sciara sp. ? 



Larva. — Length, 7-8 mm. White, semitransparent ; head glossy 

 black ; alimentary canal showing brownish on about two thirds of its 

 length; ventral view of head as in Figure i, Plate LXXX ; mandibles 

 (Fig. 8) showing but slightly above maxillary lobe; antennae in the 

 form of a circular clear area, not protuberant ; median dorsal sclerite 

 with 14 small round clear spots arranged as in Figure 10, Plate 

 LXXX ; hypopharynx as in same figure. First ganglion enclosed in 

 head ; two tracheal trunks emanating from each side of head, connect- 

 ed at prothoracic spiracle (Fig. 3), there being beyond that point only 

 one main trunk on each side ; in addition to the prothoracic spiracle 9 

 other spiracles are present on the succeeding segments (Fig. 2), the 

 fir.st and last of which appear to be closed ; body without surface hairs. 



Pupa (PI. LXXX, Fig. 4). — Length, 3-5 mm. Whitish or slightly 

 yellowish. Entire body without hairs, the usual pair on upper margin 

 of head almost indistinguishable. Prothoracic respiratory organ 

 rounded, not raised, stigmatiform. Abdominal segments 1-7 with dis- 

 tinct spiracles, apical 2 without spiracles. 



A number of larvae of this species were sent here for identification 

 from Danville, 111., at the end of July, 191 5, with the information that 

 they had been found traveling over a path in a ropelike mass. Un- 

 fortunately an attempt to rear the species failed, so that it is not pos- 

 sible to give a specific identification. It is, however, evident that it is 

 the same species recorded by Felt as occurring at Franklin, N. Y.* 



The occurrence of so-called "snakeworms" in their peculiar rope- 

 like processions has been recorded at different times by several ento- 

 mologists in America, and they have been known as occurring in 

 Europe for many years. Various causes have been assigned as respon- 

 sible for the larvae's migrating en masse ; but the most probable cause 

 is that of heavy or continued rain penetrating their habitat in the earth 



*Sixteenth Eep. State Ent. N. Y., 1901, p. 992. 



