As their name would suggest, millipedes generally have more legs than centipedes, and the segmental pairing of legs is pretty obvious. Millipedes are scavengers, so it's highly unlikely that one would bite if handled. Some millipedes are able to secrete small amounts of toxic chemicals like cyanide to protect themselves if threatened. Many insects have wings , which are NOT modified appendages, merely flaps of the exoskeleton of the meso- and metathoracic segments. There are about 28 to 30 orders of insects, depending on whose classification scheme you're using.
Insects exhibit one of two types of metamorphosis .
Those with gradual metamorphosis change from egg to nymph to adult. Larvae of these insects look very different from the adults, usually live in a totally different environment and eat different food. These have aquatic immatures, and adults with long, narrow wings. The front wings are modified as leathery tegmina , and the hind wings are membranous. These are similar to orthopterans, but without jumping legs.