Complex sentence: The colour cannot be relied on to distinguish between species because the insects sequester pigments from their food and therefore their colour depends on their diet; they accumulate uric acid in varying amounts, and this also affects their appearance.
Split into simpler sentences: The colour cannot be relied on to distinguish between species because the insects sequester pigments from their food and therefore their colour depends on their diet. They also accumulate uric acid in varying amounts, and this affects their appearance.