Hi Alex, First of all, check if there are Insecticides registered for corn in your country. I have experience with Lambda-cialotrina and Clorantraniliprole. Other Active ingredient, older one, is Clorpirifos. The rate is dependent of the concentration of the formulation that can vary among countries. One famous is LORSBAN 480. You should apply 0,5l/ha, max of 3 appl with 7 days of interval, spray volume of 100 l/ha. You should start the application when you find the incidence of 10% of plants at the level of scraped leaves. Hope it is still useful. Good luck!