Hey David,
Xpression works in layers, so rather than taking off specific ID's, you can clear a specific layer, clearing whatever graphic you have on that layer. So build all your graphics to go on a specific layer such as layer 0, then set your transitions to layer 5, and your bug to layer 10 (or 3 if you want it under your animation). So when you trigger your replay wipe send a clear layer 0 and it will remove any graphic in that layer.
To access the clear layer commands, pull up your ross talk menu, hit next (x2 - version 10 and later). and you will see channel, layer, action. since you have a prime it will be channel 1, set your layer (click down to change between all layers and a specific layer), change the action to clear.
Hope this helps.
#Carbonite