From ZooTerms (Dictionary of Invertebrate Zoology)
immature Lepidoptera and Hymenoptera, simple, ring-like spiracles with a single opening with no accessory chambers.annular spiracle: 1. In
2. In other immature insects, may be biforous, having two small or large accessory or secondary chambers usually adjacent to the margin; uniforous, when opening occurs on the margin, or multiforous if three or more openings are present.