Insect pins are used by entomologists for mounting collected insects.[2] They can also be used in dressmaking for very fine silk or antique fabrics.[3]
As standard, they are 38 millimetres (1.5 in) long and come in sizes from 000 (the smallest diameter), through 00, 0, and 1, to 8 (the largest diameter).[2][4][5] The most generally useful size in entomology is size 2, which is 0.46 millimetres (0.018 in) in diameter, with sizes 1 and 3 being the next most useful.[2][4]
They were once commonly made from brass or silver, but these would corrode from contact with insect bodies and are no longer commonly used.[2] Instead they are nickel-plated brass, yielding "white" or "black" enameling, or even made from stainless steel.[4] Similarly, the smallest sizes from 000 to 1 used to be impractical for mounting until plastic and polyethylene became commonly used for pinning bases.[2]
There are also micro-pins, which are 10–15 millimetres (0.39–0.59 in) long.[4] minutens are headless micropins that are generally only made of stainless steel, and used for double-mounting. The insect is mounted on the minuten, which is pinned to a small block of soft material, which is in turn mounted on a standard, larger, insect pin.[6][7]