Worms are defoliating my asparagus. They start at the top and work down. Are very tiny and black at first but grow to about 1/3rd of an inch long and become pale grey. I don't use pesticides, so I'm looking for an appropriate solution. I sprayed them with a 10% solution of household ammonia (nitrogen) tonight. Will check on progress tomorrow. BTW, it kills army worms (aka tent caterpillars), earwigs, slugs (and eggs), lily beetles (and eggs). So what is the name of this critter and does anyone know its life cycle? Please & Thank you.