It will be beneficial to you to clear this Infestation zone first since it can give you Fast-Travel options once you clear the Volcanic Legacy Scenic Byway NERO Checkpoint, and the Aspen Butte Ambush Camp. All three Nests are situated near each other so you don’t have to look that hard.
This is found inside a small Cave near the fire truck, by the broken bridge.
The second Nest is under the bridge, which can spawn a Breaker inside.
This Nest is found inside a delivery truck by the stream. Be warned that the water won’t slow them down compared to you so make sure you’re in the right position when engaging the freakers that will emerge from the nest.