25 bizarre facts about butterflies

Everes comyntas, eastern tailed-blue butterfly

We need more respect for insects. Let’s start with butterflies. They are easy to love. Here are 20 bizarre facts about them.

Rudbeckia hirta

1. The eyes of many butterflies have a pentachromatic colour system, meaning their receptors sense five different colour spectra (humans have trichromatic vision). 2. The petals of a black-eyed susan, Rudbeckia hirta, which look solid yellow to people, have an ultraviolet bull’s-eye effect to attract butterfly pollinators. 3. Butterflies also use ultraviolet colour to communicate with one another. Some male and female sulphur butterflies look identical to the human eye, but are sexually dimorphic in the ultraviolet range.

Limenitis arthemis (banded purple)

4. Not all butterflies like nectar. White admiral butterflies (the photo above is of a form of this species called the banded purple), Limenitis arthemis, prefer to suck moisture and nutrients from animal feces (below). 5. Their larvae and pupae imitate bird droppings.

Limenitis arthemis on wildlife dung

6. Butterflies avoid the colour green when feeding, but are attracted to it when laying eggs. 7. But just finding a green plant is not enough. Many butterfly species lay their eggs on specific host plants. Scientists are not certain how they find them. 8. Butterflies might use taste and smell, but that means they have to land and sample different plants until they find the right one. 9. It is also thought that caterpillars may develop a taste for the plants they grew on, then seek out the same taste later as an adult when laying eggs. 10. This would be an example of insect learning. 11. It is advantageous because they develop preference for a plant already abundant in the environment. 12. Agricultural mono-cropping encourages outbreaks of pest caterpillars because it provides adults (cabbage butterflies, for example) with lots of host plants in one place. Diverse plantings make butterflies work harder, as they should, while reducing economic impact.

13. Though butterfly larvae are almost exclusively phytophagous (plant-eating), the caterpillars of harvester and woolly legs butterflies are completely predatory, feeding on insects such as aphids. 14. These species associate closely with ants. In many cases the caterpillars provide services beneficial to the ant colony.

15. Symbiosis with ants is called myrmecophily. 16. One strange example is the large blue butterfly, Maculinea arion, of Europe and Asia. It begins life feeding on thyme and marjoram. Then it loses interest in eating herbs and drops to the ground. Ants find it and start milking its honeydew, then carry the caterpillar to their nest. The caterpillar continues producing honeydew, while also imitating ant smells and sounds for protection. It finds its way to the ant nursery and begins eating ant eggs and larvae. It pupates in the anthill. When the butterfly emerges, the ants escort it outside and protect it from predators while its wings unfold. 17. One caterpillar must consume about 1,500 ant grubs to mature. 18. Sometimes ants bring too many caterpillars home. They eat all the eggs, destroy the colony and starve to death.

19. The harvester, Feniseca tarquinius, is the only carnivorous species in North America. It feeds on woolly aphids. 20. The caterpillars use chemical camouflage so ants will not notice them hiding in aphid colonies.

21. A commonly-seen butterfly of eastern North America, the eastern tailed-blue, Cupido comyntas (top photo), is closely related to the harvesters. 22. It eats plants of the legume family, but also produces honeydew to placate roving ants. In exchange, ants protect the Cupido caterpillar.


23. The monarch, Danaus plexippus (above), is famous for it massive migration across North America. However, it requires three or four generations of butterflies to make the journey from Canada to wintering grounds in Mexico. 24. Most adult monarchs live only two months. The last summer generation enters a non-reproductive phase called diapause, which completes the migration, spends the winter, begins the northward trek and finally reproduces in February or March. These individuals live about seven months. 25. How generations inherit the ability to complete this journey to the same location each year continues to defy scientific explanation.

Here are two great bug websites for citizen naturalists in North America:

  • BugGuide: Can’t identify a weird bug? Try looking it up on BugGuide. There is a huge library of images. The diversity of insects is truly vast, so if you cannot find what you are looking for, submit a photo. The active community will offer suggestions.
  • Butterflies and Moths of North America: Submit photos of lepidoptera for inclusion in the database. Recorded sightings are displayed on a Google map.

3 thoughts on “25 bizarre facts about butterflies

  1. Wow, what a cool and fascinating post! I’m going to try to use the word “phytophagia” in my everyday life, as I am vegetarian. Thanks for the links. The Bug Guide looks very useful.

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