Ruddy Copper in Angel Fire NM | Photo by Steve Cary
By Steve Cary | June 2024
Most butterflies are regular flower visitors. This puts them in position to help plants reproduce by moving their pollen around from flower to flower. But “butterflies” do not function as a uniform group nor do plants. Each group of organisms is very rich in species and their members are diverse in size, shape, color, and phenology.
Plants offer nectar as bait to get butterflies and other insects to visit their flowers, but which butterflies visit? And once on the flower, do butterflies behave in ways that result in movement of pollen? As you might expect, there are no simple “yes or no” answers.
Importantly, butterflies have no interest in pollen. They cannot eat it and getting pollen into their feeding tube could interfere with siphoning nectar – the real reason for their visit to the flower. Plants offer flower nectar as bait, but once the butterfly is there, effectiveness of pollen transfer will depend on architecture of the flower as well as behavior and architecture of the butterfly.
Composite flowers (family Asteraceae) and Gossamerwings or Little Butterflies (family Lycaenidae) offer great examples of relationships that successfully feed the butterfly and pollinate the plant. The image below shows a Gray Hairstreak on a Cutleaf Coneflower, which has two convenient features for butterflies: (1) a large platform with plenty of room to stand and walk around to do the “shopping;” and (2) short nectar tubes which appeal to butterfly species with short proboscides. This Hairstreak is standing on the central cone of the inflorescence containing as-yet-unopened flowers, trying its best to stay away from the morass of dark and oddly shaped reproductive parts deployed by open blossoms around the base of the inflorescence. But its legs and proboscis are short and its fuzzy body grazes against the anthers bearing yellow pollen. Each of the tiny flowers has a tiny nectar tube and the hairstreak walks methodically around the flowerhead gathering nectar from as many nectar tubes as possible. The hairstreak’s body is fuzzy with hairs and if you look closely, you can see yellow pollen grains in the hairs and on its legs. If it is spooked off the flower by bad weather or a potential predator, the hairstreak retains a search image of this terrific plant. When ready to feed again it will look for that very same type of flower. All these structures and behaviors promote pollen transfer by this hairstreak among flowers and flowerheads of the same plant species. This exemplifies an effective pollinator/flower relationship even though the hairstreak has no notion that it is moving pollen around and pollinating the flowers.
Figure 1. Gray Hairstreak (Strymon melinus) nectaring at Cutleaf Coneflower (Rudbeckia laciniata)
Next, picture a large swallowtail butterfly, with a long proboscis and long legs, such as the Two-tailed Swallowtail featured in the photo below. Now look at the butterfly more closely. Do you see any pollen anywhere on the butterfly? On its legs, body, proboscis or face? For any butterfly, pollen is at best irrelevant and at worst a sticky nuisance, something to be avoided while seeking the sugary and nutritious nectar at the base of the flower. On most large butterflies, the long legs and long proboscis keep the body of the butterfly well away from a flower’s reproductive parts. Such butterflies zoom to the flower, siphon off the nectar and move on, leaving us to conclude that the butterfly is not moving a lot of pollen on behalf of the plant. Does this make them nectar thieves?
Figure 2. Two-tailed Swallowtail (Pterourus multicaudata) nectaring at unknown flower.
As you enjoy natural outdoor spaces in the meadows of our lovely Jemez Mountains, consider looking at insects on flowers from different perspectives. By all means, enjoy their beauty and the magic of the moment. Then you also might ask yourself an important question: is this an effective plant/pollinator relationship? Then peer in more closely, perhaps with camera or binoculars, and see if you can detect evidence of pollination.
Go to Steve’s page: Butterflies of New Mexico to learn more about butterflies
Thank you Steve very interesting and enjoyed it very much. So the butterflies main interest is sip nectar but it pollinates without its knowledge.
Hi Selvi, yes I think that sums it up. If you look at it from the plant’s point of view, they are manipulating insects (e.g., butterflies) into behaving in a way that benefits the plant. pollinators themselves get benefits, too, of course.