maraschino cherries

Question

I recently heard that maraschino cherries (the red ones used in cocktails) contains a red dye made of insect extract. Not one to take these rumors for granted, I researched the topic on the internet and found that the red dyes (Erythrosine-Red No. 3; Allura Red-Red No. 40) used to dye the cherries were chemical in composition; there was no mention of insect extract ("bug juice"). 1. Assuming for a moment, however, that the rumor was nevertheless true: This product would still be kosher, correct? 2. If so, is the reason because the dyes (ie, the insect derivatives) are inedible? 3. If that is reason, is the source for this ruling Tur/Bet Yosef & Shulchan Aruch Yoreh Deah 103? Is there a specific se'if that addresses this? (if not, what is the source?) 4. Does bittul beshishim have anything to do with this discussion? Thank you in advance for your informative answer!