This sounds a lot like signalling of some kind, like motherliness of capability of compassion or the like.
(Remark: I have just looked up the definition of phobia, and I realized that my condition is not a phobia. I don't feel any fear, just a very strong urge to avoid situations where bugs are crushed around me.)
I don't think signalling has much to do with my case. Most people find the sight and sound of bugs being crushed repulsive, and my reaction is basically the same, only stronger.
But there is probably a signalling-based explanation of why I let cockroaches go free rather than flushing them down the toilet. Flushing a bug down the toilet doesn't trigger ...
Okay, so for several years, I've been doing a fairly good job of excising out most of my irrational beliefs and fears.
The one that remains, however, is my fear of bugs and spiders. I'll SCREAM if I see one, dead or alive. And if there's one in my food, then I'm going to throw the entire plate out.
Is it common for LWers to have irrational reactions to bugs and spiders?
I know that there is "desensitization therapy", as highlighted by a Scientific American Frontiers episode a decade ago (where gradual exposure to the stimulus - a spider) - can desensitize a person with arachnophobia over time. But this can really only happen in controlled settings. In uncontrolled settings, such interaction can give you nightmares.