Smith (1874) recommended searching for stylopized bees between the hours of 9 and 12 in the morning, as according to his experiences the stylops always emerged from the body of the bee on the day on which the latter first quitted its nest, should the day be bright and sunny, and he also mentioned the fact of his never having captured a bee which had a male stylops remaining in its abdomen at a later hour than 12 m.
Source: wiktionary