Epilachna chrysomelina (Coleoptera: Coccinellidae) is a phytophagous insect with an economic importance damaging the agricultural crops. The Melon Ladybird Beetle, E. Chrysomelinais one of the major phytophagous insects that feed on cucurbit plants. It is considered an economic pest in agriculture and multi-habitat insect widely distributed throughout the world. The insect is abundant in the southern region of Saudi Arabia and choose the most favourable conditions for its life cycle completion. It prefers humid habitats with optimum temperature degrees. The generations of the insect are affected by changes in environmental conditions and its numbers increase or decline according to variation in temperature and relative humidity (RH). These factors play an important  role in changing its biological behaviour particularly feeding, breeding, reproduction and development of its generations. There were significant differences between the different developmental stages in the periods of time of their development.