Spreading advise?

The best way to spread butterflies or moths (or other insects for that matter) is to set them upside down.

Prior to setting them, the amount of relaxing time time required depends upon a number of factors including the ambient temperature, freshness and type of speciers etc. I use damp kitchen towel, not too wet, and a sealed plastic container.

I dissolve a few crystals of Phenol in the water I use to help prevent mould.

Usually 24 - 48 hrs relaxing time should be sufficient for most
specimens.

To open the wings of a relaxed butterfly or moth it is best to use a setting needle. The setting need should be held at a shallow angle relative to the plane of the wing (this will help prevent it piercing the wing ) and the point of the needle is placed under a main wing vein to gently pushush the wing into position.

I would never hold the wing with tweezers as too likely to damage it.

Johnny