I try to keep my combs in the three to four year range... but have recently read about a study that said surviveability of brood is better in older comb of five to six years... ?
Unfortunately I didn't bookmark it, and my mind is way too far gone to remember it, but I do recall wondering in what type of environment the research was done in.
I live smack in the heart of farm country, where neonics and other pesticides are used widely.
Having fields within inches of some of my hives I have never noticed a large die off from the "bloom" of dust reported to spread from the planters. I watched a plane spray the field about a quarter mile from my house last year, and watched my bees VERY closely, but did not notice any die off of any hive. Still, I don't like leaving the older wax to collect the insecticides.. I have one yard I use as a survivor yard, and I an considering leaving a couple of the hives alone to let the comb age. Is there more benefit to older comb than danger?
I think that 50% would compromise too much ability to make honey. I try to replace most comb early when I am feeding, so that by the time the bloom hits most of the new comb is already built. I do replace a little during the bloom to keep the bees busy and the brood nest open, but its still not 50% .. 25 to 30% a year replacement, and I have as yet experienced no problems with build up in the wax that I am aware of.
