The Torpid Bee

A torpid animal is dormant: this could be anything from an overwinter hibernation to a temporary overnight slowing of their bodies. Torpor helps animals to survive periods of cold temperatures by conserving their energy.

Butterflies, bees, and other insects respond to cold weather by slowing down their heartbeat and respiration thus expending less energy to keep themselves alive in a period where they cannot obtain nutrients and when it is more difficult for them to become warm.

Cold-blooded is an outdated and somewhat misleading term. The current accepted terminology is poikilotherms which means "of varying temperature". This refers to creatures with an internal temperature that varies but often matches the ambient temperature outside of their bodies. Butterflies and bees can warm their flight muscles by vibrating their wings in place, giving them some control over their internal temperatures.

When it is chilly outside, such as the temperatures in the low 40's about a week ago, insects caught outside will reach this state of torpor and remain remarkably still until temperatures rise. On cool mornings you can wander about a garden and see all sorts of creatures in this state of rest and get close enough to inspect their delicate details.

The torpid bumble bee (Bombus sp.) in these photographs was found clinging to a celosia flower in our garden shade structure. The damp morning had left tiny drops of moisture clinging all over its body, including some tiny drops on its compound eyes. The largest sphere of water clung perfectly to the back of the bee, just below its head (which made me think of a bee-version of Atlas bearing the weight of a tiny world on its back). If you expand the first two photos and look closely you can see a small upside-down field of celosia reflected in the surface of the sphere.

• The word torpid comes to us from Middle English of about the 15th century, from the Latin 'torpidus', from torpēre which means to be sluggish or numb.