Hummingbird clearwing moths are a fascinating and beautiful type of moth found primarily in North and Central America. With their long proboscis and ability to hover and feed on flowers just like hummingbirds, they have captivated lepidopterists and nature enthusiasts alike. But just how rare are these moths? Let’s take a closer look at the numbers.
Range and Habitat
There are over 120 known species of clearwing moths, with the majority found in tropical regions of Mexico, Central America, and South America. However, several species can be found as far north as Canada. In the United States, clearwings are most common in southwestern states like California, Arizona, New Mexico and Texas.
Clearwing moths tend to thrive in warm environments with plenty of flowering plants. They are predominantly found in areas like:
- Deserts
- Chaparral
- Woodlands
- Gardens
- Orchards
- Fields of wildflowers
Their dependence on flowers for food restricts them to habitats where nectar-producing plants are abundant.
Population and Conservation Status
While many clearwing species have stable populations, a few rare species have experienced concerning declines. For instance, the endangered Saint Francis’ satyr (Neonympha mitchellii francisci) has vanished from nearly half its range in North Carolina’s sandhills over the last decade. Other species like the threatened unicorn clearwing (Pterourus uno) have extremely limited habitats and small populations.
However, most clearwings remain fairly common and widespread. Out of the 120+ known species, the International Union for Conservation of Nature (IUCN) only lists 10 species as threatened or near threatened. The majority are classified as ‘Least Concern’ with stable populations.
In the United States, no clearwing species are federally listed or proposed for listing under the Endangered Species Act. While rare species like the Saint Francis’ satyr are protected in certain states, most American clearwings remain unprotected with no major threats to their survival.
Population Comparison to Other Lepidoptera
There are over 174,250 documented Lepidoptera species globally, including both butterflies and moths. Clearwing moths make up less than 0.1% of described Lepidoptera species diversity.
The total population sizes of clearwing moths worldwide is unknown. But if we compare their population trends to the broader Lepidoptera order, we can get a rough sense of their relative rarity:
- The monarch butterfly has experienced an estimated 80% population decline in the last 20 years.
- The western U.S. population of Edith’s checkerspot butterfly has declined by over 90% in just 40 years.
- Meadow Brown butterflies in Europe have declined by over 50% in under 20 years.
While some clearwing species like the Saint Francis’ satyr are facing similarly sharp declines, most appear to have much more stable populations in comparison to other threatened butterflies and moths.
Abundance in Captivity vs. the Wild
Clearwing moths are extremely popular among insect collectors. Their unique appearance and resemblance to hummingbirds makes them highly desirable. As a result, large numbers are bred and sold by commercial insectariums and butterfly houses around the world.
In captivity, clearwings can be quite common. For example, a single commercial supplier may breed and sell over 10,000 clearwings annually. However, abundance in captivity does not necessarily reflect their prevalence in natural environments.
In the wild, spotting a clearwing moth tends to be a rare and fleeting occurrence. They do not congregate in large groups like monarch butterflies. Most species are solitary and fly quickly from flower to flower, making them a challenge to observe and study in their natural habitat.
Estimated Global Population
Unfortunately, comprehensive population assessments have not been conducted for the majority of clearwing moth species. Their elusive nature makes surveying and counting their wild populations exceedingly difficult.
However, we can extrapolate very rough global population estimates based on population densities reported in a few scientific studies:
- A study of the raspberry clearwing moth in Scotland found average densities of about 11 adults per acre of raspberry plantation.
- Research on the yellow-horned clearwing in Malaysia documented up to 5 adults per acre of forested habitat.
- Studies of clearwings in Costa Rican rainforests reported densities of around 2-3 adults per acre.
If we very conservatively estimate an average density of just 1-2 moths per acre, and assume clearwings inhabit around 1-2 million acres of suitable global habitat, the global clearwing population could plausibly number 1-4 million individuals.
However, the true population is extremely difficult to pin down and may be orders of magnitude lower or higher. Overall lack of data remains a significant barrier to understanding clearwing moth conservation needs.
Probability of Encountering a Clearwing
What are the odds of seeing one of these sneaky moths in the wild? Let’s roughly estimate the probability:
- There are an estimated 1-4 million clearwings globally.
- Clearwings inhabit approximately 2-3% of the earth’s 74 million square miles of land, equaling roughly 1.5-2 million square miles.
- That means there is approximately 1 clearwing per 1-3 square miles of suitable habitat.
- But only around 10% of clearwings are active and visible at any given time based on their quick life cycle.
So your odds of encountering an active clearwing moth on a given acre of suitable habitat at any time is likely somewhere around 1 in 30 to 1 in 100. In other words, fairly slim!
In habitats with higher densities, your probability improves, perhaps to 1 in 10 acres. But the chances are still relatively low, highlighting why seeing one of these hummingbird-like moths is such a rare treat.
Conclusion
While abundant in captivity, hummingbird clearwing moths remain elusive and uncommon in the wild. A few species are threatened, but most clearwing populations appear stable. Estimated global populations likely number just 1-4 million, scattered over large ranges. With only a 1 in 30 to 1 in 100 chance of spotting one, these moths remain mysterious treasures for lucky nature enthusiasts to uncover.