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Fly Predator Questions

Life cycle

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it seems that 3- six days after I spread the fly predators the fly population declines sharply. But by day 10 to 14 they begin returning. And by day 21 the flies are back again. Do you think I should do 2 shipments per month? This is a really bad fly year for us. I have been spreading the on the muck pile and also on muck that is in the shaded areas and stays moist. Is this the most effective places. How long do the predators live? do they actually reproduce?

Thank you in advance,

Angela Bliss

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  • Angela,

    The Fly Predators are native, so they are found naturally all over the United States and Canada.  They do reproduce, but not on the scale of flies.  Each Fly Predators lays only about 100 eggs in her lifetime, compared to the roughly 1,000 eggs a fly can lay in her lifetime.  Fly Predators typically live 3-4 weeks; however, they are born with all of the eggs they will ever lay, so once they lay their full load of eggs, they generally die a little while after.

    Fly Predators only travel about 150ft max, so keeping them within 75ft of their target area is best.  Using very small amounts spread in a lot of different areas often works best.  You want to treat any areas in the pasture where manure concentrates or is beat into the ground, any wet spots, near water tanks, near areas with dense vegetation or weeks, around ponds (if they have a lot of moss or cattails), around areas where hay chaff may get spilled on the ground, etc.

    If this has been a particularly bad fly year, I would also recommend getting shipments every 3 weeks rather than ever 4 weeks to better keep up with the faster breeding flies.

    If you have any other questions, please let me know.

    Thank you,


  • If they reproduce on their own, then why do they die out? Why do we keep having to buy them?

  • Hello Joy,

    The Fly Predators do not reproduce at the same rate as flies.  The female Fly Predator lays only around 100 eggs and the female fly lays 900-1000 eggs per female so the Fly Predators just can't keep up once the flies kick into full reproduction as it only takes 8 days for a fly to go from the egg stage to an adult fly.  The fly can travel 1/4 mile in it life month life cycle and the Fly Predator can travel the maximum of 150 feet during its month's life cycle.

    So that is why you need regular shipments of the Fly Predators to continue to suppress the fly reproduction on your place.  We have a video on the website - "How to Use Fly Predators" that is very informative in explaining where flies reproduce and how to effectively apply Fly Predators.

    Please contact us if we can be of further assistance.

    Thank you,