We tend to think of butterflies as creatures that receive all their nutrition by moving from flower to flower, foraging for nectar. Carbohydrate rich nectar does give butterflies the quick energy they need to fly. But for some butterflies – particularly those with relatively long lifespans (measured in weeks or months), it is vital that they supplement their diet with different types of food. Butterflies like tiger swallowtails may be seen gathering in large numbers along damp sandy areas near waterways, engaging in an activity know as puddling. Other puddling butterflies include painted ladies, admirals and sulfurs as well as many others.
During the puddling behavior, butterflies are able to gather elements such as sodium (salt), various minerals and amino acids.
Besides sodium or mineral rich sand or mud, puddling can also take place on decomposing fish flesh, small animal carcasses, rotting fruit and mammal scat. Because of the general perception of butterflies and the symbolism attached to them, this revelation may come as a shock to some people.
Although both males and females are known to puddle, puddling butterflies are predominantly male. Other than providing butterflies with with the energy they need for their own sustenance, it is also vital for activities such as digestion, reproduction and flight.
Studies indicate that males transfer sodium and amino acids to the females during mating. Some refer to this as a “nuptial gift.” The presence of sodium is also responsible for increasing egg production and survival rate of the eggs. The salts and minerals are thought by some to be used to produce the pheromones the males use to attract females.
Any nutrients that butterflies collect must be “sipped” in liquid form since they use a long thin tube, which is a siphoning mouth part called a proboscis.
I came across my first group of puddling butterflies last week. It was very windy. Every time a gust came through, the tiger swallowtails would flatten onto their side against the ground, but they were all able to hang on and continued draining nutrients from the wet sand.