Entomology definition of Collar: in general any structure between the head and
thorax: specifically, in Hymenoptera, the neck; in Diptera, may
mean the neck, the sclerites attached to the thorax, the thorax
itself, or its processes (ante furca): in Coleoptera, is the
narrowed thorax; in Lepidoptera, applied to the sclerites
attached to the thorax and which shield the neck.