The safest way to handle a millipede is to support the whole body, keep it low over a table or tray, keep the session brief, and wash your hands afterwards. Millipedes are best handled only occasionally, because they can be injured by squeezing or drops and may release defensive secretions if they feel disturbed.
If you are still getting to know millipede behaviour, the Millipede Behaviour, Biology & Handling Guide is a useful starting point.
What to check before handling a millipede
Before you pick up a millipede, make sure it is settled and its enclosure is suitable. A deep, loose substrate, steady moisture and hiding places all help the animal remain calm and make handling less likely to be stressful. If a millipede is dry, recently disturbed or obviously unsettled, it is better to leave it alone.
It also helps to remember that millipedes are ground-dwelling animals. They are built to crawl through substrate and leaf litter, not to be carried around for long periods, so handling should always be occasional and deliberate rather than routine.
How to handle a millipede safely
Move slowly and let the millipede step onto your hand if it wants to. If you need to encourage it, do so gently and avoid pinching or gripping the body. Keep your hand steady and support the full length of the animal so nothing is left dangling.
Hold the millipede close to a low surface. If it moves suddenly, a short slip is far less risky when you are only a small distance above a tray or table. Keep the session short, then return it to its enclosure without sudden movements.
Watch for signs that the millipede wants to be put back, such as curling up or trying to retreat. If that happens, stop handling and let it settle. Afterward, wash your hands, and avoid touching your face until you have done so. That is a sensible precaution because some millipedes can release defensive secretions when disturbed.
For more on the reasons behind this, see Are Millipedes Poisonous or Venomous? and Why Do Some Millipedes Produce Defensive Secretions?
Common mistakes
The main mistakes are squeezing the millipede between finger and thumb, lifting it high above a surface, or handling it for too long. These habits increase the chance of injury and make the experience less comfortable for the animal.
It is also important to avoid handling with dirty hands or with residue from soap, insect repellent or other chemicals. Clean hands protect both you and the millipede.
Finally, do not assume every millipede will tolerate frequent contact. Some are more settled than others, but many are best enjoyed as observation animals and only handled when there is a clear reason to do so.
When not to handle at all
Do not handle a millipede if it is injured, tightly curled, or behaving in a way that suggests it is not coping well. Freshly introduced millipedes should also be left alone until they have settled in.
If you are unsure, observation is usually the better choice. A millipede that is feeding, burrowing and moving normally can be enjoyed without being picked up.