Did you ground the applicator

Did you ground the applicator with a wire to the surface where you are applying the grass or near the area?

Voltage

Also...the fly swatters might be a little light on Voltage as well.  The one I tried to modify was only about 3000V which just wasn’t quite enough juice. 

MRH YouTube

shows many ways to make and apply static grass.  Luke Towan's version seems to be a good start.

Top of this page, hoover mouse over "Goodies", and go to MRH You Tube page.  At the top of the page search for static grass applicators, and you'll get more videos than you can look at.

I'm just going to buy one. Less hassle, and time.  You have to get a good negative ion generator.  The one Luke uses has a very high output voltage.

I don't think the shape of the screen has much to do with it.

Mike.

Check your connections

Make sure you have good electrical connections and fresh d cell batteries.  Try changing you shifter screen. Try using a sink drain screen. I have used a large prescription pill bottle with a cap cut out to accept metal screen. Both of these were presented at Vermont Rails in March 2018 clinic. I do not know the clinics for 2019 yet.  The. Harbor freight swatter does have enough juice for good results. We used Elmer's white glue, do not use the school glue they are different.