Control of the Pine Processionary Caterpillar (Thaumetopoea Wilkinsoni Tams) with Diflubenzuron

During 1973-76 trials were carried out to control the pine processionary caterpillar with Dimilin (25% diflubenzuron WP), and commercial treatments with this compound in the forest were followed up until 1978/79. Total mortality of the 1st-3rd instar larvae was obtained in 8-16-year-old Aleppo pine plots after an aerial spray of Dimilin at the rate of 300 g (75 g a.i.) in 50 liter water/ha; 500 g (125 g a.i.)/ha was required to kill all 3rd and 4th instar larvae. A ground spray with Dimilin at a concentration of 0.003% (0.00075% a.i.) in water of 6-year-old Aleppo pine trees infested by 1st-3rd instar larvae gave similar results. The period Dimilin persisted on the sprayed needles in the forest was up to 27 days, even after 91 mm of rain.