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First Proof of Concept CowVac

The Story of the CowVac

By Tom Spalding, Spalding Labs

Added March 17, 2014. It might be one of the most improbable partnerships in modern dairying. A company in the beneficial insect business, teaming up with university entomologists, to introduce a revolutionary mechanical device to suck up Horn Flies. In fact, it is about as likely as a seed company starting to build tractors as the usual skill sets for bug guys don’t normally align with machinery skills. But the CowVac, its inventors, designers and manufacturer all go beyond the norm and it makes an interesting tale.

The NCSU final prototype

As anyone reading this article knows, the Horn Fly is very tough to control. It’s resistant to most every chemical control. It only reproduces in cow pastures, which means there is always productive breeding material available as no one cleans up pasture pats. It’s hugely impactful to dairies as only 200 Horn Flies per cow is the starting point of production losses and a cow can easily have a thousand Horn Flies on it. A loss of 15% in milk production has been reported during summer months and a 10% reduction in lifetime milk production has been reported from sub clinical mastitis in young stock caused by Horn Flies before the first lactation.
For the past 16 years, North Carolina State University entomologists, Dr. Wes Watson and Steve Denning, have been researching IPM practices for pest fly control for commercial livestock and poultry operations. Horn Flies have been a target for much of their work. They have seen it all, testing at least 100’s of products and numerous techniques from pesticide use on all animals, to repellent on most and only a few animals with pesticide, to using electric traps, light traps, walk thru traps, feed thru products, ear tags, oilers, you name it. They recognized the need for the Organic Dairy industry and thought there must be another way.
As they say, necessity is the mother of invention and so in 2006 as, Steve was watching flies get scrapped off cows going thru a walk in trap, and then following the cow out the exit and getting right back on, he had an AH HA moment of “let’s see if we could vacuum up those little buggers”. Steve being perhaps the most mechanically handy entomologist I’ve ever known, quickly built a test rig using a vacuum to suck up the flies as they came off when the cow went under a curtain. After several passes of the 170 cow herd, it yielded 40,000 Horn Flies and Steve knew he was onto something. That was the start of the CowVac.

Over the next 4 years Steve built ever more effective units that were more maintainable. The first ones pulled the flies through the blower fan and created quite a mess but didn’t kill them all. Later ones had a filter in front of the blower, a capture room that opened to daylight when the fan was turned off, and the flies came to that area but could not get out. Then when they ran out of energy, in about 24 hours, they died and dropped to the floor, which soon had an opening going to a collection jar. Every year Steve made improvements and the Horn Fly capture counts went up. By design, the dairy herd was next to a beef herd that was the control without any Horn Fly treatment, so there were always plenty of Horn Flies on both dairy and beef herds. As you can see from the photo, these early units were made from home improvement store parts. Organic Valley heard about this unit and they sponsored a test, placing 6 units on North Carolina dairies in 2012. Steve started building those units in the fall.
Just after that Organic Valley deal I heard about this device so I called Wes, who we had known from before, and we made a trip to Raleigh, NC to see it. I knew from our efforts using Fly Predators to control Horn Flies that this little insect was a big deal. It took a lot of work as you had to put the Fly Predators in the pastures where the cows has just been and that only worked for those doing intensive grazing. Harrowing or running a screen drag over the pastures made a big difference too, but all those things took more time than most dairymen had. If this vac thing worked it would solve a horrible problem every grazier has.

Steve Denning with Horn Flies

At NC State we saw the working unit at the NCDA/NCSU Goldsboro dairy, and the first of the units being built for OV. It was a very clever design, but needed to be redesigned to be mass produced efficiently and optimized for even higher performance. This was early October and there weren’t that many Horn Flies left but we saw the collection data which was impressive. You could control Horn Flies with just this device!

While at lunch I asked Steve how he counted all these Horn Flies. That lead to going to his pickup and when he opened the tool box it was full of 30 or more gallon zip lock bags of dead Horn Flies. Holy smokes! Part of that summer’s catch of 2.5 million to be exact. Steve was very proud of those bags of flies and being an entomologist I half expected to see them mounted on his office wall like a hunter’s trophy bucks (he hasn’t…yet). We agreed to license the technology from NC State and so began the redesign for production and optimization.
This is the second unlikely alignment of the stars. I run a beneficial insect company, but I’m a mechanical engineer (ME) by schooling and in the 30 years prior had started a number of high tech companies that built things from professional sound equipment, hot tubs, race cars, video systems, computers to name a few. Accompanying me on that first trip to Raleigh was my nephew Zac, who was also a ME. His dad was actually the founder of Spalding Labs with my mom 38 years ago, and we both grew up working in our dad’s machine shop. So I was looking forward to building a product that was very needed again.

CowVac in operation

With Zac as the chief engineer, we completely redesigned the CowVac to make it efficient to produce and much higher in performance. Using the latest in Computer Aided Design and Computational Fluid Dynamics (the same stuff you design jet airplanes with) we were able to model the air flow thru the system and over a simulated cow. We increased the flow rate by roughly double, while making the unit quieter. Some of the test runs are shown in these renderings. One of the big changes was making the airflow as non-turbulent as possible. This increased the flow and decreased the noise, but it required very smooth gradual curves in the ductwork.

However, we are a bug company and did not have a machine shop to make things. But on the first flight out to Raleigh with Zac, I had brought magazines to read and one was a metal fabrication publication. It had a story of an 80 year old Chicago company, Midland Metal Products, that had transitioned from old fashion dedicated tooling to complete numerical CAM (computer aided manufacturing). They didn’t use blue prints anymore, so we could just email them our SolidWorks files which is the CAD (computer aided design) program Zac used. Their normal business was making retail metal display racks for CVS, Target etc., but they had the latest of every automated robotic metal fabricating tool from welders, laser cutters, benders, punches and even their own powder coat paint line. They were perfect to build the CowVac. Yet, you can imagine their response to us on the first call, “you want us to manufacturer a what????”. Finding Midland was the third unlikely alignment of stars.

Computer Simulation of CowVac air

The first Spalding CowVac was ready for the 2012 International Ag Expo in Tulare, CA in February. From there it ended up replacing the NC State unit at Goldsboro, NC where we refined the airflow on real animals. While the simulated cow got us very close to optimized performance, we actually were blowing too much air on the sides and thus sending Horn Flies in many directions and not just into the vacuum. That is why the final production units have one duct per side, not the two you see in the early rendering.

The first production units were shipped to southern dairies starting in September 2012 as they were the only locations still with Horn Flies. Results were very promising, but most prospective customers wanted to see one running on a neighbor’s farm before ordering. This was still a new and strange product. In 2013 CowVacs were shipped to many states in all regions. At the end of that year I finally knew for sure that the CowVac was going to make it, as almost every installation resulted in a sale to a neighboring dairy. This article is not a sales presentation so I’ll stop here.

There is much more information on our website including videos or actual customer units in operation and results of the first University studies to be published with more coming in the next year or two. If you ever own a CowVac, you can thank NC State’s Wes Watson and Steve Denning, Organic Valley, and the lucky alignment of stars in the last quarter of 2011.

Tom Spalding is the Chief Fly Guy of Spalding Labs. This family owned business has provided Fly Predator beneficial insects for 38 years and the CowVac for Horn Fly control for the past 2 years. Prior to assuming control from his mom 10 years ago, Tom was a founder of a number of high tech businesses in music, video, computers, and internet. This diverse background is apparent when visiting their website at: Contact him at or (877) 836-9746.

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