Leather Jacket Busters Nematodes are naturally occurring microscopic worms with attitude. Each package contains the toughest nematodes on the planet which kill Leather Jacket (Crane Fly) larvae. It"s an easy 3 Step application, just open the package pour your powder into your hose end sprayer (or watering can), fill with water and spray. Leather Jacket Busters nematodes actively seek out Leather Jacket larvae in soil and reproduce to provide you with a lasting natural pest control.