67 



wide as the first and a little longer than the last, this about two 

 thirds the width of the second. Mentum deeply emarginate, with 

 acute lobes, very deeply bisulcate longitudinally. Median lobe 

 transversely corrugate. Lateral lobes with a short basal piece 

 abutting against the cardo of the maxilla. Lateral lobes with a 

 stout bristle at the anterior third; middle lobe with a smaller pair 

 of bristles opposite apex of emargination. Palpiger with a deep 

 median sulcus, each side lobe bearing a stout bristle. Palpi two- 

 jointed, joints ovate, similar. Ligula rounded, curved upward at 

 tip, a pair of stout bristles beneath, but otherwise smooth. 



Cervical shield pale brown, with a darker transverse line. Spi- 

 racles nine, first and last especially large; all of them patent. Tip 

 of abdomen flattened or slightly concave on its dorsal surface, 

 provided there with strong bristles, eight of which are borne by 

 the last segment in two rows, and four in a single row by the 

 preceding segment. 



S. parvidus. Larva. About 6 mm. long by 2,5 in width. Ex- 

 cept for size, extremely like S. ochreiis. Head much paler, — dull 

 yellowish brown; clypeus yellowish; labrum concolorous with the 

 occiput. Latter with diverging frontal vittse, less closely approx- 

 imate than, in ochreus, forming a larger pale patch posteriorly. 

 Sides of head beneath with an obscure pale longitudinal stripe. 

 Frontal suture less sinuate than in ochreiis; its angle more acute. 

 Frontal corrugations less conspicuous. Occipital black dashes not 

 bordering the vitta externally. 



DISTRIBUTION. 



The general distribution of these species has been sufficiently 

 indicated in the preceding synopsis; and concerning their occur- 

 rence in this State, I need only say that all those treated in the 

 present paper have been collected by us frequently in Central 

 Illinois with the exception of rohustus, which is rare in our col- 

 lections and has come to us only from the northern part of the 

 State. S. pertinax was taken by us also in Cook county near 

 Lake Michigan; cariosus near Cairo and in Champaign county; 

 and scAilpiiUs at Villa Eidge, in extreme Southern Illinois. Placi- 

 dvs was obtained also in the northern part of the State, — from 

 Lake and Whiteside counties. 



LIFE HISTORIES. 



The life histories of only six of our North American species are 

 even apx^roximately known, -that of parvulus most fully, and those 

 of ochreuSy periinax, rohustus and costipennis, by detached obser- 

 vations, — ochreus, pertinax, and costipennis being here first re- 

 ported. 



Parvulus is certainly single-brooded, is known to hibernate as 

 an imago, appearing in spring as early as March and April* and 



•Thin ppecifis was found hy us not uncommon un ier dead ve<retation in meadows, evidently still 

 in wintfir quarters, April Ifi, 1HH7, at Edgewood. 111. Occasionally a timothy bulb hollowed out by 

 • he larva was noticed in this field. 



