Flower preferences of butterflies

Natural History
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Do butterflies prefer to nectar at the flowers of their foodplants? Or are they promiscuous when it comes to sweets?

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That is an excellent question, which, I suppose, varies depending on the species but after some digging, I see that the general consensus is that butterflies are generally quite promiscuous when it comes to nectaring.

They do not restrict themselves to nectaring only on the flowers of their host plants (the plants their larvae feed on). Instead, they seek out a variety of flowering plants that provide ample nectar. The choice of nectar sources is typically driven by factors such as the availability of nectar, the shape and colour of the flowers, and the presence of specific compounds that might be particularly attractive to them. From the papers I checked, there are at least four determinants for the butterfly’s nectar source preference, but none of them would make them “picky” eaters.

  1. Diversity of Nectar Sources: Butterflies will visit a wide range of flowers for nectar, not just the flowers of their host plants. They often prefer flowers that are brightly coloured (such as red, yellow, and purple) and those that are easily accessible with their proboscis.
  2. Preference for High-Nectar Plants: Some plants are particularly rich in nectar and are favoured by butterflies. Common nectar sources include flowers from the aster family (Asteraceae), milkweeds (Asclepias), and lantanas (Lantana).
  3. Habitat and Seasonal Availability: The types of flowers available in a butterfly’s habitat and the season will influence their nectaring choices. Butterflies are opportunistic and will take advantage of whatever flowers bloom and provide nectar at any given time.
  4. Feeding Behavior: While nectaring, butterflies are primarily seeking energy in the form of sugars, but they may also derive other nutrients and chemicals that can be important for reproduction and defense.

So, while butterflies are not particularly loyal to the flowers of their food plants, they do show preferences based on the nectar quality and accessibility of the flowers.