THE WASMANN JOURNAL OF BIOLOGY

VoL. 19, No. 2 FALL, 1961

Report on Spongilla-flies at Clear Lake, California (Neuroptera: ) *

THOMAS S. ACKER, West Baden Unive1·sity, W est Baden StJ?·ings, Indiana.

Spongilla-flies have been collected rarely in California. Chand­ ler ( 1953 ) first reported their presence in the state through his description of the new species Climacia californica. He had taken larval specimens from fresh-water in May of 1947; two years later on May 19 he secured adults as well as larvae and pupae. The type locality was well defined : southwest end of Clear Lake near J ago's Resort where the waves from the prevailing wind beat against the boulders on a rocky point. In the Cali­ fornia Academy of Sciences' collection there is one earlier un­ reported specimen of this species. It is marked, "Lower Lake, Cash Creek, May 10, 1926." This creek is undoubtedly that which goes by the name Cache Creek on our maps today; it is at the extreme southern end of Clear Lake and only a mile and a half from Jago's Resort. Aside from these records no other species of Sisyridae have been reported from California. In an effort to :find further specimens of Climacia cali[01·nica this writer, during· four successive years (1957-60), visited the type locality at Clear Lake. Two trips were made each year, both in May. Despite careful searching of the rocks for pupae and beating of the overhanging vegetation, no specimens of Climacia califoTnica were ever taken. However, another species of spongilla­ :fly, Sisym vicaTia, was found on several occasions. The following are the :first collecting records of this species from California : (1) southwest end of Clear Lake, Lake County, California, 9 pupal specimens taken from the underside of rocks that formed a

*This investigation was begun with the assistance of a Public Health Research Fellowship of the National Institute of Allergy and Infectious Diseases and completed under a postdoctoral Public Health Service Grant. [ 283] 284 THE W ASMANN JOURNAL OF BIOLOGY, VoL. 19, 1961 jetty at the north end of the J ago Resort property, May 24, 1958; (2) 17 pupae and 1 adult (hidden beneath the rocks) were taken from this same locality and another rocky area just below one of the Jago's lakeside resort cabins, May 16, 1959; (3) 1 pupa from the jetty region, May 29 , 1960. The populations of Sisyra vicaria seem very low, for these numbers of specimens represented a search of many hours over the rocks. Many of the pupae later emerged as adults and were preserved in alcohol. On July 25, 1961, a diligent search was made again for any Sisyridae at Clear Lake. Although the fresh-water sponges on which the sisyrid larvae feed were examined, pupae searched for on the reeds and rocks, and the bushes beaten at Jago's Resort and also at Rocky Point just south of there, no spongilla-flies were found . Even the spider webs which meshed the shoreline bushes gave no sign of neuropteran insects although these same webs were heavy with remains of gnats, trichopterans, and an occa­ sional large bee. From the positive and negative collecting dat.:'l. here reported, two interesting points may be made: (1) Chandler (1956) stated that Sisym vica1·ia would prob­ ably be found in the northern part of California althouO'h at that time it had not been reported. These California records of Sisyra ...... ' ... vicaria complete Chandler's statements and help to intermediate the localities of Oregon and Arizona where this species had previ­ ously been recorded ( cf. Parfin and Gurney, J 956). (2) In seeking some explanation for the apparent absence of Olinwcia californicct, there is reason to suspect the gnat-control program which is carried on at Clear Lake by the Lake County ifosquito Abatement District. The Clear Lake gnat, Ohaoborus astictopus Dyar & Shannon, occurs at high population levels at the lake, and annoyance by the tiny insects of this species affects the resort attractiveness of the region. In the fall of 1949, 40,000 gallon of a 30 per cent DDD formulation were put on the lake. 'l'hrough natural current, wind action, and diffusion, a uniform concentration of .02 ppm. was achieved. In 1954 and 1957 a simi­ lar program was followed. Chandler (1953 ) reported that larvae of Olimacia califo·rnica were taken from sponges at Rocky Point after the first application of DDD and that apparently the species was not destroyed. However, in December of 1957, a local game SPONGILLA- FLIES AT CLEAR LAKE, CALIF.-ACKER 285

warden discovered a number of dead Western Grebes on the lake ; their tissues were found to contain high concentrations of DDD. The tissues of local game fish likewise had accumulated the in­ secticide and continued use of this product could have developed into a public-health hazard. For this reason the DDD program was discontinued in 1958 and replaced by spraying· the gnat egg drifts with Richfield Larvicide. For a longer summary of the Clear Lake gnat control program confer Dolphin's report (1959). Dolphin states that the DDD treatment achieved 100 per cent re­ duction of the gnat larval population in the first two treatments and a 96 per cent reduction in the 1957 treatment. It is difficult to believe that such a radical gnat-control program could do any­ thing else but reduce the populations of many other insects (such as the spongilla-fiies) that complete part of their cycle in the lake. Even though Chandler reports that Clirnacia californica larvae were found between the first and second DDD treatments, there is no mention of the relative abundance. My own search for the species indicates that if it has not disappeared from the type locality where formerly it seemed not uncommon (although rarely collected owing to its specialized locality), its population is dras­ tically reduced. It is interesting to speculate as to why Sisym vica1·ia may have survived while Clirnacia californica has not. Brown ( 1952), in his study of Clinwcia a1·eolaris, mentions that while the same , Spongilla fmgilis, occurred both in the relatively cool, clean Lake Erie and in the relatively warm, pol­ luted Haunck's Pond on Middle Bass Island, sponges from the lake yielded only Clirnacia larvae, whereas sponges from the warm, shallow pond yielded only Sisym larvae. Thus one might suspect that the Clirnacia is more sensitive to pollution than is Sisym. Furthermore, it might be noted that since wave and wind action were utilized to spread the DDD and Clirnacia califm·nica was found where the waves from the prevailing winds beat against the boulders, this species was probably subjected to heavier and longer standing concentrations than Sisym vica1·ia which was taken in the more protected cove of J ago's Bay. In any event it is hoped that more effort will be put into basic research of the gnat problem rather than a continuation of radical chemical con­ trol which appears to alter the ecology of California's largest fresh-water lake. 286 THE WASMANN JOURNAL OF BIOLOGY, VoL. 19, 1961

REFERENCES CITED

BROWN, HARLEY P. 1952. The life history of Glinwcia m-eolaris (Hagan), a neuropter­ ous parasite of fresh water sponges. American Midland Naturalist, 47(1) :130- 160.

CHAND.LER, H. P. 1953. A new species of Glinwcia frollll California (Sisyridae, Neu­ roptera). Journal of the Washington Academy of Sciences, 43 ( 6) :182-184. 1956. Aquatic Neumptera. In: Usinger, R. L., Aquatic Insects of California, Chapter 9, pages 234-236. Berkeley, Calif. 508 pp.

DOLPII!N, ROBEllT 1959. Lake County Mosquito Abatement District Gnat Research Pro­ gram. Proceedings and Papers of the Twenty-seventh An­ nual Conference of the California Mosquito Control Associa­ tion, Inc., pages 47-48.

PARFIN, S. 1., and A. B. GURNEY 1956. The spongilla-fiies, with special reference to those of the wes­ tern hemisphere ( Sisyridae: Neuroptera). Proceedings of the United States National Museum, 1958, 105:421-529.