Sand flies are small; a body size of about 3 mm in length is typical for many species, which aids them in escaping notice.

Their bite is not always felt, but leaves a small round, reddish bump that starts itching hours or days later.

[2] As sand fly females suck blood from vertebrates, including humans, they can transmit leishmaniasis, arboviruses and bartonellosis.

[2] In the New World, leishmaniasis is spread by sand flies in the genus Lutzomyia, which commonly live in caves, where their main hosts are bats.

[citation needed] Phlebotomine sand flies can be found between the latitudes 50°N and 40°S, but are absent from New Zealand and the Pacific Islands.