The Zygoptera (damselflies) are small to medium-sized insects with a slender abdomen and eyes positioned on the sides of the head. This gives the head a halter-like shape. In most families (with the exception of the Calopterygidae), the short-stemmed, almost identical front and rear wings are folded together above the back when at rest. Only the damselflies (with the exception of the winter damselflies) keep them half-open.