If you’ve had an unusually wet spring and temperatures are now ramping up, house flies are coming!  Below is the who, what, when, where, and why and how to help reduce the impact.

Who’s going to be most likely to have problems with house flies?  

Anyone who has received a lot of rain and has warming temperatures, especially if you have had flooding or standing water that has been preventing manure clean-up and or removal or keeping manure in pastures damp.

What exactly is coming? 

House flies can be a nuisance because they bother our animals faces, sit on everything, and bug our food, but they do NOT bite.  House flies may cluster around horses’ eyes or around areas other biting flies like horse flies and stable flies have already drawn blood.  Aside from the nuisance factor, house flies can also spread many types of bacteria that can make people sick.  Females of these flies can lay up to 150 eggs at a time and lay several clutches in a lifetime.  That means every female biting stable fly has the potential to produce nearly 1,000 offspring in her lifetime!

When is this population explosion of house flies likely to happen?  

NOW!  If you’ve had a wet spring and have been starting to get hot during the day, you’ve probably already noticed flies hanging around.  If you don’t have them yet, they’re going to start very soon.

 Where are all these flies coming from?!  

House flies like to breed in manure, food waste, compost, spilled feed, and other areas of decaying organic matter.  Unlike biting stable flies, house flies do not breed abundantly in areas of only decaying vegetation. 

Why are things worse this year? 

With extra rain and flooding, areas that typically dry out before a house fly can complete its lifecycle are staying damp long enough to churn out one or more generations of house flies.  For example, single piles of manure in pasture that normally dry quickly may be staying damp for over a week due to standing water, saturated soil, and dense plant matter.  Similarly, if you normally spread your manure, if you’ve had a wet spring, areas where manure was spread may not be drying out like before.

How can I reduce the impact?

#1 Sanitation, sanitation, sanitation!  Try and keep manure picked up as much as possible, even in turn outs and pastures.  While it is wet, pile manure rather than spread.  Piled manure will begin to compost and generate heat, which can kill developing fly larvae.  If possible, turn the edges of piles up to the top every few days to thoroughly cook larvae surviving in the cooler outer edges.

 #2 Add more Fly Predators to match the much higher number of fly larvae (maggots) that survive to the pupal (cocoons) stage.  This happens due to the moisture of manure and other rotting organic matter remaining in the 40%-60% range.  If you are unable to pick up pastures or turnouts, you will want to try and get more Fly Predators out in those areas.  Remember though that Fly Predators only travel about 150ft, so it is better to spread very small amounts in many places in the pasture until things dry out enough to where manure is completely dry all the way through within 5 days or less.

Because we are expecting flies to be so much worse this year in the really wet areas, we would suggest increasing your Fly Predator quantities to help keep up with the increase in fly production.  If your next shipment is more than 2 weeks away and you have a huge fly problem already, we would suggest an additional shipment now. To find your shipment schedule online login HERE with your email. If you don’t remember your password click “I need help with my password” just above login box.

If you would like to make these changes to your order, please email orders@spalding-labs.com and let us know how many of your remaining shipments to double or increase by 50% in total and if you would like an extra shipment now. Please give us your name, phone # and zip code too.

If you would like to speak to us, please call 1-800-737-2753.  We expect to be very busy with calls and apologize in advance if your call goes to voice mail due to all agents being on a call. Please leave your name, phone # and zip code and we will call you back.

#3 Add traps.  House flies can be caught with a couple types of common traps.  One is odor traps such as the Terminator Pro, Giant Fly Relief Bag, and Trap N’ Toss by StarBar, the other are yellow sticky traps such as the EZ Trap by StarBar.  However, it is very important to use both traps in appropriate places.  Odor traps are the smelly traps you add water to. These traps are attractant traps that draw flies in from some distance.  Because of this, DO NOT place odor traps within 100-200 ft of barns, buildings, homes, or other areas you want to keep flies away from.  Instead, use odor traps to draw flies away from those areas by placing them around 150-200 ft away.  To trap flies already nearby, use yellow sticky traps.  Yellow is an attractive color to house flies but will not attract flies from a distance, so these are ok to use inside barns and other buildings.  

Watch our How to Use Fly Traps.

 #4 With flies coming in from off your property, you may also need to resort to fly spray this year. Our new Bye Bye Insects Fly Spray is the first essential oil spray that matches the performance of the very best synthetic Pyrethroid sprays.  But unlike those, it can be used on yourself and your horses. It’s also effective for Mosquitoes. It smells nice too.!  If house flies are getting in your home, you can spray Bye Bye Insects around the door frames to repel flies hanging out near there waiting to zoom in when the door opens.  Bye Bye Insects will stain light colored hair on horses, so we do not recommend use on white, gray, or pinto show horses or horses where staining is a problem.  The staining does wear off, but does not wash off.


This helpful blog is by our amazing entomologist Jessica Starcevich! Thanks Jess!!!!

Biting Stable Flies are also going to be excessive for regions who experienced extra wet Springs coupled with temps rising up now, so check out specific for those pests as well! Click HERE!