Lovebug, Plecia nearctica Hardy

Plecia nearctica (Fig. 1) is the lovebug that motorists frequently encounter as a serious nusiance when traveling in southern states. It was first described by Hardy (1940) from Galveston, Texas, and at that time he 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. Hetrick (1970a) studied the biology of P. nearctica, and estimated that flights reached altitudes of 300 to 450 meters, extended several kilometers over the Gulf of Mexico and covered one-fourth the land area of Florida. Today it is found throughout Florida. It has been erroneously reported that the lovebug was introduced into Florida by University of Florida entomologists. Buschman (1976) documented the progressive movement of the lovebug around the Gulf Coast into Florida (Fig. 3). Research was conducted by the University of Florida and U.S. Dept of Agriculture entomologists after the lovebug was well established in Florida. It was first collected in Florida during 1949, in Escambia County, the westernmost county of the panhandle.

Thompson (1975) reported over 200 species in the genus Plecia. There are only 2 species of Plecia in the U.S.A., P. nearctica and P. americana Hardy. Their ranges are similar, but americana extends northeastward to North Carolina and south to Mexico, whereas nearctica ranges farther south to Costa Rica. P. americana is a woodland species that does not seem to be a problem on highways. Each of 2 generations of P. nearctica lasts about 4 weeks in May and September. In addition to large emergences in May and September, it has been collected in Florida every month of the year except November (Buschman, 1976). Buschman stated that throughout its extensive range, P. americana has been collected only in April, May, and June, with no evidence of a fall emergence. Thus, lovebugs that emerge in the fall are P. nearctica. He added that most of the spring collection dates of P. americana in north central Florida are 2 or 3 weeks earlier than similar dates for P. nearctica. A description and key to these two species are provided at the end of this circular.

Another bibionid, Dilophus sayi Hardy (1966) [=Dilophus orbatus Osten Sacken; =Philia orbata (Osten Sacken)] is a March fly (Bibionidae) in which the behavior of the adults is somewhat similar to that of P. nearctica, but the adults do not congregate noticeably on highways. In Florida, populations of D. sayi peak from late January through April, but can be observed most of the year beginning with cooler weather in October. Most Florida records are in the peninsula south to Dade County. D. sayi is smaller than Plecia spp., and has an all-black body, lacking the reddish color of the thoracic region of Plecia. The males of D. sayi are smaller than the females and have clear wings as opposed to the brown fumose wings of the females. We have observed D. sayi attracted to recently parked cars in Gainesville, Florida, and to barbecue grills. Thornhill (1976a) in studies at Gainesville, Florida stated that aggregates of up to 300 larvae of D. sayi could be found on or near the surface of the soil among the roots of grasses. Under lab conditions females lived about 72 hours and males about 92. Both Thornhill and Rothamel (1969) gave details on orientation and coupling of D. sayi. This bibionid attains nuisance numbers as adults in Florida and elsewhere from South Carolina south and west to Texas and California. Complaints about the larvae and adults of D. sayi (reported as D. orbatus) were statewide in California during October of 1970 (USDA, Cooperative Economic Insect Report 20: 797). In this same volume of C.E.I.R., there were numerous reports of it being a problem during autumn in sod and lawns, including one report of 1,000 larvae per sq. meter in a nursery at Oakland, Alameda County, California. This species, however, is of minor importance, compared to P. nearctica, which is a major nusiance on Florida highways.