Starting Late? Read This Guide

If You Are Starting Fly Predators Late in the Season Here Is What You Need to Know

Fly Predators are a fly preventative. Fly Predators kill developing flies, but do not affect adult pest flies that are already flying around. This means you need to go after both the future flies with Fly Predators and existing flies with Fly Traps and Spray to see a quick reduction. If using Fly Predators alone, the existing flies have to die off which can take 30 days or more.

Why it can take 3 or more shipments to see a difference

Fly Predators attack the fly when it has recently transformed from a maggot to a young pupa. Fly Predators will feed on some of these pupae and lay eggs in others to let their young feed on and kill the developing fly. This means that adult pest flies that have already emerged and older pupae are not vulnerable to Fly Predators. Next year the best time to start Fly Predators is just before the first hatch of flies. We have recommended starting dates for every zip code here.

If you are starting your order late in the season and already have a lot of flies out, it usually requires a larger starting dose of Fly Predators (2-3 times the recommended for current animal quantity) and will take about 3 shipments 3 weeks apart to start to see a real difference. This is due to a combination of factors.

First, it takes a couple weeks from the time the first Fly Predator emerges to when all the Fly Predators in the package will have hatched, so that first population has a whole lot of work to do if there are already a lot of flies out. The lag in hatching is because we use 3 different species in our Fly Predator mix that have slightly different development times depending on temperatures. The species used in Fly Predators were chosen so that there would be species that search the surface (Muscidifurax zaraptor and Muscidifurax raptorellus) as well as species that dig down deeper in their search for pest flies (Spalangia endius and/or Spalangia cameroni).

Second, because Fly Predators attack specifically the young pupal stage of the pest fly, there will be a period where adult pest flies will continue to emerge, because their pupa was too old to be attacked by Fly Predators during that initial release.

Third, those new flies and the current ones must die before you will notice the reduction in population overall. Flies live approximately 30 days. See our video on using Fly Predators here.

Can I speed up the process?

Absolutely, start by using traps to help catch adult flies and lower their population faster! See our video on using Fly Traps HERE

Plan on using at least 2 and possibly 3 different trap types. For House Flies, the ones on the face of your horse going for the moisture in their eyes, but also found everywhere, use Odor Traps. These are the ones you add water to that smell bad. However, make sure to never put odor traps inside or within 150ft of buildings and animals. Odor traps are designed to attract flies from a distance, so you use them to draw flies away from an area. Odor traps indoors can end up inviting more flies to join the party. Yellow sticky traps are great for use against house flies inside the barn and common use areas.
The flies biting your animals’ legs and flanks and dog’s ears are Biting Stable Flies. They only are caught by The Bite Free Stable Fly Trap which should be placed very low to the ground (the top should be no higher than your hip) and in good afternoon sunlight. Stable fly traps should be placed outside, near where animals hang out, but on the opposite side of the fence to avoid them playing with the trap.

Fly baits and premise insecticides can also be used if you don’t mind pesticides. These are available from most feed stores. A good device is the StarBar Fly Abatement Stick in that the pesticide is contained in a cage that flies can reach but kids and pets cannot. Fly baits should be placed in a disposable container out of reach of pets or livestock and should not be used outdoors on the ground where it can seep into the ground as they can be drawn up in plants and cause harm to honeybees. Premise insecticide sprays can also be used on areas where flies like to rest. If there is a particular wall or area where you see a lot of little black specks from the flies, that is a good location to spray with an insecticide to kill adult flies. Be sure the read the label completely and follow all instructions for use.

What should I do first?

Quite honestly call us at 1-866-404-3903! Our agents are all fly experts and can help you determine what types of flies you have (different flies breed in different habitats), where best to spread Fly Predators, and offer advice on the best management practices based on your set up and location. We can still make a big difference this year if you have 2 months of fly season left. And you will be prepared with the knowledge for a delightfully fly free next year.

Spalding Labs

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