Abstract: To study the quantitative impact laws of environmental or genetic factors on the insect body color, we must first solve the measurement problem of characteristics of the standardized values of the insect body color. If different researchers who determine the color do not use the uniform standards, no matter what method is used, such as genetic, molecular, physiological or ecological methods, etc., to study it, the results would be potentially misleading. In order to solve the problem that nearly a thousand kinds of insect body colors with continuous changes can not be described accurately and computed reasonably by the text and mathematics, this study adopted the color measurement technology of international standard-PFG (Pantone Formula Guide) color guide as the criterion of insect body color trait, and proposed some evaluation indicators on numerical description of insect body color, such as body-color element (BCE), body-color group (BCG), body-color position (BCP), highfrequency color-code index (HFI), variegated color index (VCI), etc., and some quantitative analytical methods. Using these indicators and methods, we studied the differentiation diversity, change process and numerical law of the body color on different body positions of different larval individuals of sweet potato hawk moth Agrius convolvuli (Linnaeus) at different developmental ages under similar environmental conditions. It was found that A. convolvuli larvae had a common main body color. The body color variation occurred mainly at different developmental ages in the individuals, accounting for 72.66% of the total variation. The difference of body color on different parts of an individual was also significant, accounting for 24.45% of the total variation, while the color difference among individuals at the same developmental age was very small, accounting for only 2.88% of the total variation. The results indicate that the process of color change occurred with the developmental stage of A. convolvuli larvae may be a process of appearance performance of an organism’s body from development to senescence determined by the genetic factors.

Key words: Agrius convolvuli, larval body-color, body-color differentiation, numerical analysis, evaluation index