This is a common horse fly with an early flight season. It is a widespread and abundant species in most of North America, found in a variety of wetland sites. It is a severe pest of livestock and humans (Teskey, 1990).

H. lasiophthalma takes a mean blood meal of 82.8 mg (Hollander & Wright, 1980a). In one study in Tennessee, it fed mainly on the lower body (70%) and on the face (26%) of cattle (N=386 observations, Mullens & Gerhardt, 1979). Along with other Hybomitra spp., interactions with cattle were studied by Ralley et al. (1993) in Manitoba, on the same pasture  as McElligott & Galloway (1991a, b). There are many further studies that document H. lasiophthalma as a common pest of livestock in the USA. Magnarelli & Anderson (1980) described feeding sites (mostly on the back and sides - different from what was found above in Tennessee) , and documented the frequency of disrupted feeding (32%) on cattle in Connecticut. They identified 23 of 31 blood meals as having come from bovines, with the rest from deer and horse. Tashiro & Schwardt (1953) found it to be the most abundant tabanid attacking dairy cattle in New York, taking an average blood meal of 116 mg (N=135). 

Thomas (1972, 1973) in Alberta, Troubridge & Davies (1975) in Ontario, McClean et al. (1975) and Magnarelli (1976) in New York, Magnarelli & Anderson (1981) in Connecticut, and Leprince & Bigras-Poulin (1990) in Quebec documented seasonal reproduction and/or sugar feeding. The species is anautogenous, producing eggs only after intake of a blood meal. Thompson et al. (1980b) reared the species from Texas. Teskey (1969) provides information on the biology of immatures and their habitats in Canada.

H. lasiophthalma was one of the common species present during the exploratory studies leading to the development of the Manitoba horse fly trap (Bracken et al., 1962). Behaviour towards colours, shapes, etc. was documented in Manitoba, and in a later study in New Brunswick (Browne & Bennett, 1980). Thompson (1972) and Roberts (1972) provided information on catches in various kinds of traps in the USA. Small numbers were caught in a comparison of box and canopy traps in North Carolina (Axtell et al., 1975). This species was captured in small numbers in carbon dioxide baited CDC light traps set for mosquitoes in Wisconsin (Amin & Hageman, 1974).

LePrince et al. (1991) reported catches of up to 7,512 H. lasiophthalma per day in carbon dioxide - baited canopy traps in Louisiana. Hribar et al. (1992) reported a 45-fold increase in catch through the release of carbon dioxide (1,631 flies per day, versus only 36 per day in an unbaited trap). With a few exceptions, mean catches of tabanids in most traps rarely exceed hundreds per day. Lastly, McElligott & McIver (1987) studied the range of attraction to carbon dioxide in Ontario (in the absence of a visual target). Their results imply a very short range of attraction (e.g. 3 metres), which is difficult to interpret relative to the large increases in catch with traps (i.e. with a visual target present).

Foil et al. (1984) reported that H. lasiophthalma was the only tabanid present during one seasonal outbreak of equine infectious anemia (EIA) in Louisiana. Kemen et al. (1978) demonstrated experimental mechanical transmission of EIA among ponies using this species. Foil (1989) reviewed the role of tabanids in the transmission of viral and many other diseases. Krinsky & Pechuman (1975) cultured epimastigote trypanosomes from this species in New York that were most likely bovid Trypanosoma theileri parasites. Thompson (1978, 1979, 1980b) documented sarcophagid and bombyliid larval parasitism of H. lasiophthalma, and Clark et al. (1984) isolated spiroplasmas. Iranpour & Galloway (2004) described new species of Telenomus parasitoids of eggs, and Iranpour et al. (2004) described DNA techniques for identifying egg masses.

Hybomitra lasiophthalma

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