There are no instructions included with the Bug Catchers beyond the pictorial diagrams printed on the front of the tester.  The pictorial diagrams are typically sufficient to explain and understand the usage of the device.  Operation of the tester is fairly intuitive if you are familiar with continuity testing cables. 

 

The Top row of lights indicate the pin-out of the signal being sent and the lower row of lights indicate the pin-in of the signals being received by the tester.  Rotating the knob in the center determine which pin-out is activated.

 

The Red light to the far left indicates short to case ground.

 

The Green light to the far right indicates battery condition.

 

The one possibly confusing test is related to testing TS 1/4" cords in the 1/4" TRS jacks and takes some getting used to.  I know it's a little confusing, but I didn't have room to put another TS 1/4" jack on in addition to the TRS 1/4" test jacks, and the TRS test jacks will work fine for testing TS cables if you do it right.  On a good TS cable the # 2 position will work normally.  In position # 1 both # 1 lights should illuminate as well as the top # 3 light.  In position # 3 both # 3 lights will illuminate as well at the top # 1 light.

 

See... the basic problem with testing TS cables with a TRS tester is the ring (R) part of the test jack.  The ring (R) part of the tester is wired to the #3 lights.  The left side of the tester receives, and the right side sends.  When you stick a TS cable in the TRS tester, the ring (R) is shorted out on the sleeve (S) of the TS cable.  Since the Sleeve (S) is indicated by light #1 the right side is sending a signal down the sleeve (in the 1 position) and the left side reads a signal on the ring (3) and sleeve (1) indicator lights.  This is normal.  Of course if you get 1 & 2 happening, or 1 and nothing, then your cable is bad.

 

Of course, you could insert the TS cable just part way and test the tip of the TS cable with the ring contact point, then just use lights 1 & 3.