I used to believe that flower nectar was sugary water and not much else. That simple drink should be adequate for many of the insects that visit flowers. Sugar provides the fuel to power their flight, thus taking care of a fundamental need. Many insects have a very short adult life. They have already accumulated, during their larval life, most of the nourishment that they need as adults. In fact there are even some insects, such as the Luna moth, that do not feed at all as adults. Moreover, nectar drinkers often have other foods in their menu. For instance, bees collect pollen, as well as nectar, from flowers; wasps hunt insects. So it wouldn’t be surprising if nectar provided nothing more than sugar as a reward to pollinators.
I was wrong, but I wasn’t alone in my ignorance. Only recently, scientists have been able to study the chemistry of nectar, given the tiny amounts available for study. What they have learned in recent years surprised everybody. Nectar is a true cocktail including an assortment of substances, from nutritious to intoxicating, not to mention scented, colored or with preservatives. Flowers are known for the complexity and diversity of their shapes and colors. Now we know that their nectar can be just as rich in complexity and variety. Nectar drinkers seem to be connoisseurs of the restaurants they visit and flowers must have good reasons for developing such a complex menu to satisfy the demands of their clientele.
First of all the concentrations of sugars vary depending on a number of factors. Perhaps, the most important one is the most frequent visitors of a particular species. Butterflies and moths and some bees have very long tongues which they use like drinking straws. They visit flowers that provide a rather watery drink not likely to clog these very thin pipes. On the other hand, other insects, with shorter tongues, merely lap or slurp fluids and can take advantage of thicker nectar, richer in sugar.
In addition to sugar there are other substances in nectar. Like the power drinks used by athletes some contain ion supplements, such as potassium and sodium. Other common supplements of nectar are aminoacids, the building blocks of proteins. Let us remember that adult butterflies and moths cannot eat any solids. They have no chewing parts, only a long, thin tongue good enough for fluids and maybe the occasional pollen grain. As I mentioned before, most insects are short lived and may do fine without proteins in their diet, but the beloved monarch butterflies live for several months and have to make an arduous journey. They certainly need a well balanced diet; sugar alone would not suffice them.
There are other ingredients in nectar which I will discuss in future posts. I only want to mention here that in addition to nutrition, these substances may add flavor to this food making it more attractive to the pollinators and other flower visitors.
It is rather amazing to realize that we didn’t invent energy drinks; flowers did it millions of years ago. It gives me pause when I prepare to refill the hummingbird feeder. Are we turning our loved birds into soft drink junkies? Would they be better off without our help? I don’t feel too guilty because I know that they also feed on insects so they must be getting a balanced diet despite the empty calories at the hummingbird feeder. But, just in case, I will start growing plants for hummingbirds in my garden and cutting down on the junk food.
I can think of a few (natives only): butterfly weed, lobelia, beebalm, columbines, trumpet honeysuckle, penstemon, zinnia, nicotiana. Any suggestions?
Here is a list of “Top Ten” native hummingbird plants of the Operation Rubythroat web site.
Nectar, a drink with a zing
Nectar, the first soft drink
Tiny treeshrews chug alcoholic nectar without getting drunk
List of articles
© Beatriz Moisset. 2012