<p><span style="font-size:14px"><span style="font-family:Arial,Helvetica,sans-serif">The Melon Ladybird Beetle, <em>Epilachna chrysomelina</em> (Coleoptera: Coccinellidae) Fabricius, is one of the major phytophagous insects that feed on cucurbit plants. <em>E. chrysomelina</em> which is considered an economic pest in agriculture is a multi-habitat insect widely distributed throughout the world .It is also endemic along the Southern and the Western coast of Saudi Arabia due to the abundance of cucurbit plants (wild and domesticated) where it passes through all four developmental stages . In this research it was found that temperature and humidity affect the insect biological activities through their effect on insect reproduction and development. During some parts of the year the insect is more abundant due to the favorable conditions of temperature and humidity for reproduction. The month of March was more favorable than February while January was the least favorable.</span></span></p>