How many letters does the top answer for “large swift fly the female of which sucks blood of various animals” have?

The most common answer is clegg (5 letters).

Crossword clue: large swift fly the female of which sucks blood of various animals

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

clegg 5 letters wn-def

large swift fly the female of which sucks blood of various animals

horsefly 8 letters wn-def

large swift fly the female of which sucks blood of various animals