If you see a swarm of small black insects bobbing up and down in the air, you may well be observing the mating ritual of March Flies, also known as Lovebugs. These flies belong to the family Bibionidae, and the majority of species emerge in the spring, hence their common name. (In the Northeast, many appear in April and May.) However, there are certain species which emerge and mate in the fall and they are active now.
March Flies are dimorphic. Males (fly to the left in photo) are easily discernible because of their large eyes, essential for finding mates and chasing competing males. Males comprise most of a swarm, performing an aerial ballet as they bounce up and down, courting females as they emerge from the ground en masse. Once mating has taken place, the male and female of certain species remain attached to one another, even in flight. This is where the name “Lovebug” came from.