242 PROCEEDINGS OF THE NATIONAL MUSEUM Von. 113 
elongate and elliptical pale brownish scales. Tibiae rufopiceous, 
covered with linear whitish scales. Tarsi black, covered with silvery 
white scales; third segment much broader than first two; fourth seg- 
ment extending well beyond third. Median lobe of male genitalia 
rather convex dorsally, internal sac covered with small spines (fig. 64). 
Stem of the spiculum ventrale of female genitalia not expanded at 
its anterior end (fig. 112). 
MerasurEmMeEnts: The following measurements were taken from 8 
males and 5 females from Woodland, Calif. (USNM), 2 males and 1 
female from Davis, Calif. (USNM), and 1 female from Sierra Madre, 
Calif. (CAS). All measurements are in millimeters: 
Males Females 
Mean Extremes Mean Extremes 
Body length 1. 80 1. 80-2. 20 1.84 1. 65-2. 10 
Elytra length 1. 44 1. 30-1. 50 1.37 1. 15-1. 50 
Elytra width at base 0. 84 0. 73-0. 89 0.79 0. 73-0. 83 
Prothorax length 0. 53 0. 49-0. 59 0.48 0. 43-0. 56 
Prothorax width 0. 62 0. 56-0. 66 0.57 #0. 53-0. 63 
Rostrum length 0. 73 0. 66-0. 79 0.73 0. 63-0. 79 
Rostrum length before antennal 0. 22 0. 20-0. 33 0.31 0. 26-0. 40 
insertion 
Funicular segment 2 length 0.045 0. 034-0.051 0.040 0. 034-0. 051 
Funicular segment 3 length 0. 034 0. 034 
Briotoay: The biology of this species is unknown except for a few 
records of plants on which this species has been taken. ‘‘Pyracantha 
blossoms,’ Davis, Calif., May 5 (USNM);‘‘Coll. on Pinus monophylla,”’ 
Argus Mountains, May (USNM); “swept from Alfalf.,”’ Sacramento, 
Calif., Nov. 21 (USNM). 
Discussion: S. instabilis may be readily distinguished from the 
other species in the S. instabilis group by the single patch of white 
scales and oblique line of white scales on each of the elytra. In the 
case of badly rubbed specimens in which most of the scales are miss- 
ing, it may be necessary to compare their genitalia with figure 64 
(male) or figure 112 (female) in order to identify this species. 
Distripution: S. instabilis has been recorded from the coastal re- 
gion of California, the California Valley section and (1 record, Bass 
Lake, Calif.) from the Sierra Nevada section, all in the Pacific moun- 
tain system. ‘The following specimens were examined: 
CALIFORNIA: CONTRA CosTa Co.: July (CAS). FRESNO co.: Fresno, May 3 and 
18(USNM). rnyo co.: Argus Mountains, May (USNM). Los ANGELES Co.: Los 
Angeles (USNM); Pasadena, March, April, June, Oct. (CAS); Redonodo, March 
(CAS); Sierra Madre, March, April (CAS). MapERaA co.: Bass Lake, July 8 
(CAS). ORANGE Co.: Newport, April 10 (CAS). sAcRAMENTO co.: Sacramento, 
Nov. 21 (USNM). SAN BERNARDINO Co.: Colton (CAS). SAN DIEGO co.: Coro- 
nado Beach, July 26-27 (CU); Poway (CAS). oxo co.: Davis, May 5 and 13; 
Woodland, May 13 (USNM). Southern Calif. (CM). Lower Calif. (CM). 
Total specimens examined: 102. 
