74 
THE PAN-PACIFIC ENTOMOLOGIST 
AN ASTONISHING HOVERING RECORD FOR MALES OF THE WESTERN HORSE FLY, 
PILIMAS CALIFORNIO A (BIGOT). — During a lecture to our Society on 15 November 1974, 
entitled “Life in a 300-Foot Giant Sequoia,” our present President, Ron Stecker, included 
films of insects he observed and collected in the upper canopy of a giant Sequoia tree 
located near the southern margin of Sequoia National Park at about 1800 meters altitude. 
His 11-year studies received considerable attention in the scientific community and the 
media. He showed one fly species hovering above the very top-most stem (under 
precarious circumstances for collecting and filming at a height of about 90 meters!), 
which appeared to me to represent the hovering green-eyed, holoptic males of a rather 
primitive, though not uncommon, western horse fly, Pilimas californica (Bigot). In the past, 
others and myself have netted such males while they were hovering in sunlit patches 
along forested roadways and mountain trails, or open-wooded, sunny spots, such as a 
camp-site in Yellowstone Park. This obvious mating behavior pattern has resulted in 
capture by collectors of many more males than females from British Columbia and 
Montana south to Utah and California. I have also seen a female in the collection of CAS 
taken by Dr. Paul H. Arnaud, Jr. in Baja California: Agua Caliente (San Carlos), 18.5 km E 
Maneadero, 5 August 1973. 
But that the males might be hovering in an undoubted mating quest at the top of a giant 
Sequoia towering some fifty meters above the surrounding forest canopy seems rather 
incredulous; the frequency of such behavior is not likely soon to be checked. Since 
females are not known to similarly hover, it is reasonable to presume that at least they fly 
by as high as the questing males. Not quite parallel are the habits, familiarto many of us, 
of scarcer males of more aggressive species of horse flies, hovering over bare, rocky 
knobs or objects like fire lookouts on tops of high mountains; for example, I took the 
previously unknown male of Hybomitra sequax (Williston), among other species, on top of 
Blue Nose Peak on the Montana-ldaho Divide in this way. 
Dr. Stecker recently brought me five of his flies for checking. All were males of 
californica taken just above his tree-top post. Understandably, he was able to net only a 
small sample (approximately a dozen specimens) during the eleven years of observation 
atop the sequoia, which dominated the adjacent evergreen forest on a slope some 20 
meters above a small creek bottom. 
Two of his males, plus a female, are being passed among the audience. Finally, 
projection of a Kodaslide copy of a frame from Dr. Stecker’s movie shows one close-up 
male sitting on a branch which not only reveals the previously mentioned green, holoptic 
eyes and bright body colors by which I guessed its identity during the original movie, but 
attests to the flies also coming to rest in the upper branches of the sequoia during 
hovering, and probably mating activities. It is trite to point out to tabanidologists that the 
males at this height are considerably removed from breeding sites where they could have 
emerged from pupae; the habitat of the immature stages at ground level has never been 
reported. — CORNELIUS B. PHILIP. California Academy of Sciences, San Francisco. 
A FOSSIL OF SCAPHINOTUS INTERRUPTUS FROM THE PLEISTOCENE CARPIN- 
TERIA ASPHALT DEPOSIT, SANTA BARBARA COUNTY, CALIFORNIA (COLEOPTERA, 
CARABIDAE). — A single well preserved abdomen of Scaphinotus interruptus (Menetries) 
has been found in a study of the fossil insect fauna of the Carpinteria asphalt deposit. 
This specimen provides a good example of Pleistocene paleoentomology. Studies of 
Pleistocene insects can provide much useful information (Coope, 1970, Ann. Rev. Ent. 
15:97-120), but this field has not received much attention in North America. 
Fossil deposits were discovered in the Carpinteria asphalt mine in 1927. This mine was 
located on a coastal bluff about one mile southeast of the town of Carpinteria, in Santa 
Barbara County, California. The mining operation was later abandoned and the site was 
used as a refuse dump in the late 1940's, so that today the topography has been altered 
drastically and the fossil localities are not accessible. Although a series of reports were 
published on the fossil flora and fauna, the fossil insects have never been examined in 
detail, except for a study of termite signs (Lance, 1946, Bull. S. Cal. Acad. Sci. 45:21-27). 
The unanimous opinion of the published reports dealing with the various fossil groups 
is that, while organisms were being preserved late in the Pleistocene epoch, the environ¬ 
ment at Carpinteria was very similar to the present environment of the Monterey 
