Vermilingua minjupii

Here's a small mystery.
It's getting to that time of year when the retic needs some attention.
So I ran my usual annual test yesterday morning.
Several of the micro jets were blocked.
Nothing for it but to take them off and suck/blow through them to clear the blockage.
But what causes this during their winter/spring downtime?
They work fine up to about June, then go into hibernation.
When you try to use them again, they're stuffed up.
How does the crap get in there when they're not in use?
My personal taste test suggests a non-very-pleasant answer.
Ants.

Sledge