Last March I did a Flying Squirrel job on a HUGE 3 story house and generally failed miserably. It's not that I don't know how to do Flyers as I've had many successes but this one went bad from the start. I was never able to identify THE access hole and in general the house is very tight with an excellent gutter helmet system. I set probably close to 20 traps in the attic of various kinds with various baits. For probably two weeks I monitored the traps...during that period the homeowners never heard a thing and I never caught a Flyer. So I closed every hole I could find and really felt like the house was sealed. Most of the exclusion involved closing off ends of the gutter helmet system, caulking cracks between siding and soffit etc. About a week ago I got a call back and went in the attic. While there I saw 2 Flyers...so positive ID for sure. It has rained here for days so I started again with baited traps in the attic and again...nothing caught and nothing heard by the homeowners.

I KNOW I have to find the access hole and will start going over the exterior first chance I get. One thing that I will need to check closely is that they have added a screen porch to the rear since I first worked there so maybe something has changed. I'm wide open for suggestions. I hate failure and call backs. The client is completely understanding and 100% pleased with my effort so hope to keep it that way.

Metal roof? Ridge vent wired under? I'm sure pictures would help recieve good advice on possible entries.

Roof is architectural shingles. Continuous ridge is not wired under but is the "good" kind (I forget the brand) and end caps are in place. Will try to get some pics and post in a few days.

Check the entire shingle edge

Entire gutter line has good gutter helmet so shingle edge is not "approachable". As best I can tell all ends, edges etc of gutter helmet system is sealed for Flyers. Downspouts have screens as well.

I agree Rick but from looking from the inside of the attic there is virtually no construction gap and frankly with my health issues I'd rather refund their money than take all the gutter guard down and replace it! The rear of the house is 3 story and eats up all of my 40 foot ladder. Yes to checking soffit returns, gable vents, apex etc.

Don't forget to check low as well. My first flyer job had them entering the house through a hole in the siding at ground level then climbing up into the attic.

Ditto on the low entry points for flyers. I've found them entering through crawl space vents under decks (chewed through screens on slider-type crawl vents), and they also crawl up inside the metal shroud that covers A/C lines and enter where the lines pass through the soffit.

However, they are no different than working with bats regarding the exterior inspection. If you can't access every inch of the structure (not talking about binoculars, either) then you will not solve the problem. You need to get to EVERY soffit transition and see if you can "lift" the soffit panel at the end of the channel. They are typically just laying in the channel and flyers will squeeze right in.

Here's a pic of a dead flyer under an A/C line shround. Had a flap of skin stuck on a self-tapping metal screw that was protruding into the shroud.






EDIT: I've also had grays entering using the A/C shrouds. Not just flyers!

Ron and Eric beat me to it. Check low. I had some coming in via a tough to find foundation hole under a deck, into the crawlspace, across the vapor barrier, and up the chimney chase thru another hole, and into the attic. Nearly quit the business over that job. It was frustrating the bejeezus out of me.
This house you're working on, is any part of it vinyl or aluminum sided by chance? Have you checked the bottom end of the corners? Typical entry point around here for mice, rats, and snakes. We use Kritter Kaps or Xcluder and sealant to barricade those entry points.
Good luck.