A North American Glowworm (Orfelia fultoni).
A variety of invertebrates go by the name of “glowworm.” One kind of glowworm in North America is a larval mycetocephalid fly, Orfelia fultoni. The larval flies spin a web like a spider, hence another common name, “web worm.” Also like a spider, they eat the insects that they capture in their webs. To attract insects to their webs, glowworms have two “lanterns” in their bodies that produce a bright blue light. The light draws nocturnal insects into the webs, where they are consumed by the larval flies. This species was photographed in Alabama (2010).
''Orfelia fultoni'' is the only bioluminescent species of fly found in North America. It is distantly related to ''Arachnocampa'', and their bioluminescent systems use distinct mechanisms. The larvae of the species live in stream banks among moss and rock cavities, as well as in wet sandstone caves. They build sticky webs, and using their two bioluminescent lanterns as an attractant, capture flying prey. They produce the bluest light of any studied bioluminescent insect. The species occurs in the.. more