Bend a body pin by steel wire
attach the foam on the pin
build up the body, wrap two over the foam then one wrap forward the foam, repat until the body of lenght is satisfying
whip finish then pull the foam body of the pin.
Add a pieace of floating material into a pieace of mesh cloth
make it to a ball, then attach to the hook.
make some tread wraps to build up two eye balls.
attach the pin foam body to the hook shank
add three brush legs.
take a suitable burner and burn the wings.
tie in the wings, if needed add some superglue to fixate the wings in right positions.
Congratulations you just made a horsefly!