If man eater bug is the only monster you have face down and want to tribute it will flip effect activate thus killing before can it?

You are correct! If you want to tribute summon a monster using Man-Eater Bug as tribute, its flip effect will activate before it can be used for the tribute summon.

Here's why:

* Flip Effects Activate Immediately: When a monster is flipped face-up, its flip effect activates immediately, before any other actions can be taken with it.

* Tribute Summon Trigger: You only start the tribute summon process *after* the flipped monster's effect resolves.

Therefore:

1. You flip Man-Eater Bug face-up.

2. Man-Eater Bug's effect activates and destroys itself.

3. Man-Eater Bug is no longer on the field, so you cannot use it as tribute fodder.

Note: You can still use Man-Eater Bug as tribute fodder if you can prevent its flip effect from activating, such as using a card that negates the flip effect.