Transportation and Maintenance of Fly Predators


Fly predators are shipped still developing inside the host, packed in a bag or pouch, and mixed with wood shavings for protection. Depending on the temperature during shipment, parasites will start hatching 4-10 days after arrival. Warmer temperatures will make them hatch faster, while cooler temperatures will slow the hatch. Keep the closed bag in a warm place (around 70 degrees F.) out of the sun until you notice some movement inside.


Start releases when some of the fly predators have hatched in the bag. Flies lay their eggs in areas that stay moist and have a food source for their growing pupae. Good areas for release of the fly predators are in manure piles, around water tanks, around walls of arena and stalls, etc. Simply sprinkle the contents out of the bag. If direct sun is a problem, covering the pupae with dirt or organic matter is advised.


Predatory flies will not travel farther than about 150 ft. Placing the pupae at the fly hatch locations is critical.  I encourage you to scout your property and think like a fly!

My recommended calendar for release 2018

 (7-8 Fly Predator releases per year.)

  • April

  • May

  • June

  • July

  • Check on the manure compost mid July to see if we need to boost the predator population.

  • Beginning to middle of August

  • September

  • We will watch fall conditions to see if an October release is advised.