The research aim was to identify the influence of extract concentration of orange skin on the population density and the attack intensity of the larvae P. xylostella. The research was conducted from June to September 2004 in Bobo Village, Palolo Regency, Donggala District, Province of Central Sulawesi. The research used a Completely Randomized Design with 5 treatments replicated 3 times, thus, there were 15 experimental units. The levels of extract concentrations were without extract as a control (A), 10% extract concentration (B), 20 % extract concentration (C), 40 % extract concentration (D), and 80% extract concentration (E). The research results showed that the extract of orange skin significantly decreased the population of the P. xylostella larvae. The best treatment was the 80 % extract concentration than other application.