How to Flush Bugs Out of FRESH water lines?

I have a 1998 2518 and am finally getting it ready for summer camping. Last winter I flushed and drained all the water but I left all the drains open all winter. Now I have bugs or spiders that have made a home in the cold water lines!

I managed to disassemble both the kitchen and bathroom faucets and got 6-8 bug chunks out (big enough they barely lit through the hose but wouldn't go through the faucet). My problem now is the shower.

Hot water flows through the shower but the cold water is almost totally blocked with debris. I can't figure out how to get to the connections on the shower control!

I took off both handles and the top of the shower leaving me with a piece of white PVC that is somehow attached to the backsplash.

I have tried blasting air from an air compressor from the shower into the control with the cold full open, but it doesn't budge whatever is blocking it.

Any words of wisdom on how to clear the blockage would be appreciated. I am eager to go camping!

Thanks,

Dean