Since there are no seasons at the equator.
I think it would depend on slight changes of tempreture in the year. Also each species has an 'internal clock' that alows them to send of the alites at the right time.
well there is a raining season so maybe just before or after it
the tropics have wet/dry seasons, but some equatorial regions are pretty much uniform all year round.
depends on many diffrent factors, diffrent species require diffrent conditions, some at night, some at mid day, some in the morning etc etc, some like it hot and humid, some like it cool and dry
Generally the Wet seasons have the most flights
Like miszt said, the wet season would have the most flights, the ground is much softer than and so it is easier for the queens to dig themselves in.