As Ann states, Methyl cellulose is by far the strongest and safest glue. We alsouse heat activated adhesives such as Fusion 5000. These are brought up to 180 degrees F. with a tacking iron. They are stronger then Methyl cellulose, but I don't know if it is worth the bother for insect labels. The heat activated adhesives are also archival and completely reversible.
Book binders use it constantly.
It is not reversible, butneutral, and will never release. Cheers, Craig Z ammiello Larvae. I put the recipes of 2 fixation fluids on the list, beacuse it may be of general interest. I would greatly appreciate if more colleagues would use this stuff. Larvae thrown in boiling water are completely useless for study of internal structures.