[odfrank]

I was given a topbar hive that was directly sprayed, unknown pesticide. The story was a swarm moved into an empty hive and the neighbor sprayed it.. I scrapped it, I soapy water washed it, hot pressure washed it, rinsed it and let sit out in the sun a few months. No residue problems. It swarmed yesterday.

 

[JClark]

Most insecticides used today can be "decontaminated" through a simple detergent wash. If the insecticide was an organophosphate or carbamate you'd need to use an ammonia solution to decontaminate.

If a long lasting residual was used then you may need to do as above before use. Some products, once dry, are designed to not wash off--at least in the case of permethrin treated clothing. Really would help to know what was used.

Either case, I would not save any wax that may have picked up residual.

 

[Saltybee]

Let the ants clean out mine. They will get in a closed hive.

 

[Jack Grimshaw]

You don't say where you
are located.Nor do you say how your bees were exposed.Was the actual hive sprayed or did they spray you neighbors dandylions?Try to get the name of the chemical used.You may be able to get compensation and the applicator could be fined.
Most states take bee kills by pesticides very seriously .In Mass,for instance,because of Covid 19,all bee inspections have been cancelled except for imports,Foulbrood and Pesticide kills.Contact you state inspector
(If you have one!) immediately.
Most bee kills come from direct exposure to the insecticide while foraging,next comes bee contact with previously sprayed floral resources,then with contaminated nectar and pollen brought back to the hive.
It is rare that hive parts are contaminated although you could have contaminated stores.
Too often beekeepers shout pesticide kill and then don't follow through.Sloppy pesticide applicators won't be stopped unless we make a big stink.Again, contact your state officials immediately.They need fresh samples.
(40+ years with a Supervisory Pesticide License while keeping bees)