I finally got the Rare Golden Spider, my last _bug_! I'd tried all the tips and waited a long, long time, and got nada, so went away and played with Fish Tycoon and my villagers and such for a couple of days. Tonight I came back prepared for a long siege, but lo and behold, the Spider came along within an hour of playing with the ridgeballs. I did have a little more variety of ridgeballs tonight, though.. before I had only venomous, aureus, and four-petal rb's, but tonight I added blazing and mela. Who knows?
Oddly, when I went to admire my pretty new spider, I found it's the only _bug_ in the display that doesn't move when the cursor comes near. I was a little disappointed, wanted to see it in all its glory!