DEVELOPMENT,LIFE HISTORY Life History and Seasonal Abundance of Fannia benjamini Complex (Diptera: Muscidae) in Southern California BRADLEY A. MULLENS AND ALEC C. GERRY Department of Entomology, University of California, Riverside, CA 92521 J. Med. Entomol. 43(2): 192Ð199 (2006) Downloaded from https://academic.oup.com/jme/article/43/2/192/1060117 by guest on 27 September 2021 ABSTRACT Seasonal abundance and life history of Fannia benjamini complex (Diptera: Muscidae) was studied in the coastal mountain community of La Habra Heights in Los Angeles County, California, with additional observations in drier, inland mountains in the Woodcrest area, Riverside County. The dominant species (Ͼ95% of ßy collections) was Fannia conspicua Malloch, whereas Fannia benjamini Malloch also was present. Both species could be collected nearly year-round by netting adults (almost exclusively females) attracted to people, although F. benjamini was relatively more common in cooler weather (NovemberÐApril). In La Habra Heights, adult activity peaked in June and July (both species), whereas peak activity in Woodcrest was late April through June for F. conspicua and February through April for F. benjamini. Field-collected adult females provided only water died within 2Ð4 d, whereas females provided with water plus a dry milk and sugar mixture survived up to 128Ð130 d in the laboratory. Males of F. conspicua (1Ð40 individuals) swarmed at heights of 0.5Ð4.0 m near Aptenia cordifolia (L.f.) Schwantes, an exotic, succulent, low-growing ground cover plant. Eggs of F. conspicua were deposited singly on older, decaying leaves of this plant, and adult F. conspicua emerged from Aptenia-covered areas in the Þeld. In the laboratory, larvae of F. conspicua grazed on microbial surface Þlms associated with Aptenia. Emergence of F. conspicua from Þeld-collected soilÐAptenia mixtures (held in the laboratory) occurred from 1.5 to 5 mo after collection. Widespread Aptenia planting since the 1980s has probably resulted in F. conspicua becoming a severe human nuisance in some areas. KEY WORDS Muscidae, Fannia, Fanniinae, Aptenia THE Fannia benjamini Malloch complex (Diptera: tions of their orientation to feeding tabanids, two- Muscidae) is found primarily in upland coastal moun- dimensional visual targets, and survival and fecundity. tain and Sierra foothill habitats of California, with However, there have been no systematic studies of some distributed in Baja, Mexico, and Arizona (Chill- “canyon ßy” activity. The immature development sites cott 1960). Commonly called “canyon ßies,” they in the Þeld have remained unknown, with the excep- range from 3.5 to 4.5 mm in length, and the complex tion of a single pupa of F. benjamini taken from a wood consists of seven species (Turner 1976). One member rat nest (Chillcott 1960). The current study was de- of the complex, F. thelaziae Turner, supports devel- signed to determine species present in selected loca- opment of nematodes (eyeworms) in the genus Thela- tions in southern California, to document their sea- zia, which infect a variety of mammals, including peo- sonal adult activity, and to investigate other life history aspects, particularly immature developmental sites. ple (Weinmann et al. 1974, Turner 1976). Where they are abundant, these ßies also are very signiÞcant hu- Materials and Methods man and animal nuisance pests, ßying around and sometimes landing on the face and other parts of the Study Sites. Primary study sites were two residences and a horse riding ring area in coastal mountain habitat body. in the city of La Habra Heights, Los Angeles County Despite their abundance and pest status, very little (33Њ 57Ј N, 117Њ 57Ј W, 280-m elevation). This area has is known about “canyon ßy” biology. Winkler and numerous hills and canyons with both endemic and Wagner (1961) reared F. benjamini complex from eggs exotic trees, including coast live oak, Quercus agrifolia derived from wild-caught females, and superÞcially Nee; sycamore, Platanus racemosa Nutt.; Brazilian described larval development in the laboratory. Poor- pepper, Schinus terebinthifolius Raddi; and Eucalyptus baugh (1969) reared F. benjamini through two labo- spp., with arroyo willow, Salix lasiolepis Benth, and ratory generations, describing some aspects of its im- black willow, Salix nigra Marsh, in the drainages. The mature development, laboratory mating behavior, and natural habitat in treeless areas is coastal sage scrub, larval feeding behavior. Garcia and Rodovsky (1962) where common plants include California buckwheat, observed adult feeding behavior of wild-caught adult Eriogonum fasciculatum Benth, and California sage- female F. benjamini and made preliminary observa- brush, Artemisia californica Less. The area receives 0022-2585/06/0192Ð0199$04.00/0 ᭧ 2006 Entomological Society of America March 2006 MULLENS AND GERRY:CANYON FLY LIFE HISTORY 193 Ϸ41 cm of rainfall per year, and Ͼ80% of this rainfall water in a vial, 4) liquid whole milk on tissues plus 10% occurs between November and April. Average high sugar water in a vial, and 5) fresh beef liver plus 10% and low air temperatures in January are 20.8 and 7.6ЊC sugar water in a vial. The liver and whole milk were and in July 28.0 and 17.3ЊC, respectively. replaced every 2 d. Flies were maintained at 23 Ϯ1ЊC and Other observations were made in the Woodcrest natural photoperiod and monitored every 1 to2dfor area of western Riverside County (33Њ 53Ј N, mortality (dead ßies were removed) until all had died. 117Њ 21Ј W, 430-m elevation). This area is topograph- The numbers of adult females dying in the different food ically somewhat similar to La Habra Heights, but is treatments were subjected to survival analysis. drier, hotter in summer, and cooler in winter. Natural Observations on Mating Behavior and Immature areas (without irrigation) have essentially no trees Development Sites. Observations of male swarming except in the drainages, where sycamore, Eucalyptus behavior (location, time of day, and approximate num- spp., and black willow are common. The sage scrub ber of individuals) were made in the Þeld in May and habitat is more sparse but with many of the same June 2003 and 2004 in Woodcrest, and in July 2004 at Downloaded from https://academic.oup.com/jme/article/43/2/192/1060117 by guest on 27 September 2021 plants. The area receives 27 cm of rain per year, also the horse riding area in La Habra Heights. almost all between fall and spring. Average high and Large, tent-type emergence traps (Fig. 1) were de- low temperatures in January are 19.6 and 5.7ЊC and in signed and deployed in spring and summer 2004. July 30.7 and 17.3ЊC, respectively. Fiber-reinforced, brown plastic tarps (either 1.5 by Seasonal Adult Activity. Because adult “canyon 2.2 m or 2.5 by 3.1 m) formed the “skirt” of the trap and ßies” are attracted to the vicinity of people or animals, had a 12-cm hole cut in the center. Marine plywood their activity was documented by collecting ßies at- (two layers each 1.9 cm in thickness) was used as a top. tracted to the researchers using a short-handled, 45-cm The rectangular plywood pieces (25.4 by 15.2 cm) had diameter aerial sweep net. Collections initially were holes cut and offset toward one end- the top hole was made from both residences and the horse riding area in 10.9 cm in diameter and the bottom hole was 11.7 cm La Habra Heights. Weekly collections were made be- in diameter. A Þtted 2-liter clear polystyrene jar lid ginning 13 May 2003 and continued through 14 August (screw top) nested tightly in the opening, and a con- 2003. Collections continued at the horse riding area ical piece of clear plastic was formed into a cone and were made every 2 wk between 26 August and (glued to the lid) to impede exit of ßies that made their 29 January 2004. Weekly collections at the horse riding way into the trap container. One side of the jar itself area resumed on 4 March 2004 and continued through had a hole 9 cm in diameter and covered by 16 mesh 19 August 2004. Collections generally were made in the window screen to provide ventilation. The jars thus morning between 0900 and 1030 hours. could be easily removed and capped with a solid lid to On each sample date, a researcher stopped for 5 min obtain collected insects. at each of four consecutive, regular locations situated The tarp was held securely between the two pieces 30Ð75 m apart. Flies attracted to the person were of plywood, which were fastened together using bolts. collected by net, killed in a cooler with dry ice, and The underside of the plywood end opposite the hole placed in a labeled vial for transport back to the lab- had a metal screw base afÞxed, and a 1.3-cm-diameter, oratory for counting and identiÞcation. Flies were sturdy plastic pipe was screwed into it. The pipe was identiÞed using keys in Turner (1976) and through 61 cm in length for the larger tarp and 46 cm in length comparison with identiÞed material in the California for the smaller tarp. Academy of Sciences, San Francisco, CA. To deploy the trap, a 1-m-long piece of metal re- The two researchers were compared in La Habra inforcing bar (1 cm in diameter) could be hammered Heights for attraction and netting efÞciency on three into the soil, and the pipe slid down onto it. This formed dates in July and August 2003. On those dates, the two a tentlike center pole. Tent stakes were pounded researchers stood Ϸ4 m apart and netted ßies for through the grommet holes at the edges of the tarp, matched 5-min periods (n ϭ 10).