Seasonal Flight of Plecia nearctica (Diptera: Bibionidae) in Southern Florida

Abstract

The lovebug, Plecia nearctica Hardy, is a serious nuisance to motorists traveling in southern states. The insects are smashed against windshields obscuring vision and cars may overheat when radiators become clogged. The smashed insects also damage car paint if the body fluids are not removed soon after contact (Callahan and Denmark 1973). The insect was first described by Hardy (1940) from Galveston, Texas, who reported it to be widely spread, but more common in Texas and Louisiana than other Gulf Coast states. It has now progressed to all states bordering on the Gulf of Mexico, as well as Georgia, South Carolina, and parts of Central America. It was first collected in Florida in 1949 and today is found throughout Florida (Denmark and Mead 1992). Adult flights of lovebugs have been reported to occur primarily during May and September in different areas of the insect's range (Hetrick 1970; Callahan and Denmark 1973; Buschman 1976; Thornhill 1976; Callahan 1985). However, in spite of these previous reports, no data have ever been presented actually showing seasonal flights of the lovebugs. Our objective was to determine seasonal flight patterns of P nearctica in southern Florida. Additional data on temporal sychronony of flights at different locations are also presented. Yellow sticky traps (Pherocon AM, no bait) made by Trece Inc., Salinas, California and baited with anethole (Cherry 1998) were used to monitor adult flights of lovebugs. Sampling was conducted by putting out 15 new sticky traps each month at approximately mid-month. These 15 traps were located at three different locations (5 traps/ location) to provide data on temporal synchrony between locations. One location was the Everglades Research and Education Center (location one), University of Florida, located near Belle Glade, Florida. The other two locations were located approximately 24 km southwest of the research center (location two) and 31 km east of the research center (location three). All three locations were located within Palm Beach County, Florida, and surrounded by agricultural lands (sugarcane, rice, vegetables). Traps at each location were placed 250 m apart in a straight line (i.e. a one km transect) adjacent roads. Each trap was hung one m above the ground on a metal rod and had a sponge (3 x 3 x 3 cm) containing 5 ml of anethole wedged into it. All 15 traps were hung and baited on the same day and collected seven days later. The seven day exposure period was used to avoid short term inclement weather factors such as rain, extreme winds, etc. that might greatly reduce adult catches within a shorter trap exposure time. Traps were collected by wrapping each trap in clear cellophane in the field. Lovebugs on each trap were counted by microscopic identification in a laboratory. A sample of lovebug adults collected on the traps during different major flight periods (May, September, December) was sent to Dr. Gary Steck, Division of Plant Industry, Gainesville, Florida who corroborated that the insects were P nearctica. Statistical analysis was conducted by SAS (1996). Temporal synchrony of adult flights between locations was determined by multiple correlation using the total number of adults caught each month at each location. Differences in mean numbers of adults caught at each location during different months were determined by using Tukey's test. A figure to visually show the overall seasonal flight pattern of the lovebugs is also presented. Although different numbers of lovebugs were observed between locations (Table 1), there was temporal synchrony in flight between locations. Multiple correlation of