My kiddo has a lot of fears, but hers are mostly SPD sound related, and my DH is scared of heights so I understand when you say phobia.
I'd avoid Stitch too if a trigger is something touching you. And probably the Haunted Mansion and possibly Pirates for the cobwebs if that's part of the fear.
I hate bugs. They squick me.
And they adore me.
I'm the one who ALWAYS gets bit. Was bit pretty bad a couple of months ago in bed, luckily my kiddo who cosleeps with me was not but I had a terrible allergic reaction to the bites that lead to an asthma attack and then extra time visiting my allergist. Sigh.
We have both wolf and brown recluse plus the black widow here in Chicago and they're common. Our condo is currently covered in spiders because the current person in charge reset the outdoor lighting so it's completely lit up and there's lots of buzzing night bugs for them to eat. It's like a gauntlet for me to walk inside. Or out. I try to keep calm so I don't pass my horror to our 3 yo but it's really hard to do. They suspected it was a brown recluse that bit me.
So for me, the only good thing about a long brutal winter that is projected is we'll have months free of them.
You might want to get a blacklight flashlight to check out the room for your son before you check in so he feels it's safe (I do this anyway because of the possibility of bedbugs. I swear bugs LOVE me and I'm not bringing that nightmare home!). You can also pick up one or five of those bug noise plug in things that are supposed to keep bugs away. Not sure if it really will, but he can believe it, right? And peppermint scent is supposed to repel spiders so if it helps him, maybe a scented spray? Worst thing is you'll have a minty-scented kid who feels secure.
Fair warning, we saw several random spiders at Animal kingdom with pretty impressive webs when we were walking around.
And also 2 snakes at Epcot. My 3 yo was most impressed with them all. Good luck to you. I know fears are super hard.