The effects of the insect 20-hydroxyecdysone and juvenile hormoneⅢ on reproduction of pine wood nematode,Bursaphelenchus xylophilus,were investigated. The nematodes were treated with 7 continuous geometric concentration series of 20-hydroxyecdysone or juvenile hormone Ⅲ. The numbers of the nematodes treated with 20-hydroxyecdysone or juvenile hormone Ⅲ from the 6th day to the 9th were significantly higher than those of the blank control and the control treated with only the nematode food,Botrytis cinerea( P...