Complex sentence: In 1961 there was drought, and in 1962 rain continued through the dry season, allowing a massive build-up of the "Stomoxys calcitrans" biting fly by May 1962.
Split into simpler sentences: In 1961 there was drought, and in 1962 rain continued through the dry season. This caused a massive build-up of the "Stomoxys calcitrans" biting fly by May 1962.