New Hawk Moths Are Some of the Smallest Ever Found

Some of the largest moths in the world are hawk moths. They have thick bodies, long narrow wings, and are acrobatic and fast when they fly.

Although the insects are distinctive because of their size, some new, much smaller members of the family were recently discovered. Three new species uncovered from the Bahamas are some of the tiniest ever found.

Researchers from the Florida Museum of Natural History discovered the new species, which are about the size of a vitamin. They were sifting through the museum’s hawk moth specimens to identify the ones from the Bahamas and sort data by island.

“It is critical that we survey habitats and areas which are threatened by environmental change so we can document what is there now, while it is still there, and have a baseline for comparison as conditions change,” study co-author Deborah Matthews, a biological scientist at the museum, tells Treehugger.

“Habitats in the Bahamas, like the Florida Keys, are being lost due to development such as housing, golf courses, and tourist facilities and are further threatened by sea level rise, increasing frequency and intensity of hurricanes, and prolonged drought.”  

They compared DNA, anatomy, and wing patterns on those they found to other species of the same Cautethia genus that is from the Caribbean.

“Within a species, there can be a lot of variation in colors and wing patterns. When we sorted specimens of this group genus by island, we noticed some slight differences in wing patterns on some of the more distant islands,” Matthews says.

“By dissecting anatomical structures of the abdomen, we were able to see some more obvious differences. DNA studies also confirmed species-level differences.”

Researchers realized they had three distinct, undescribed species.

“In terms of moths, the giant silk moths and hawk moths are very popular and well-studied, kind of like the butterflies of the moth world,” Matthews says. “So, for us to find three new hawk moth species, that’s a really big deal.”

The findings were published in the journal Insecta Mundi.

All About Hawk Moths

Hawk moths are also called hummingbird moths or sphinx moths. They are found in many habitats around the world and have been named for the way they hover and fly quickly. Some can even fly backward.

There are more than 1,700 species of hawk moths. They have wingspans from 2 to 8 inches (5 to 20 centimeters.

Hawk moths have the longest tongues of any moth or butterfly, with some as long as about a foot unfurled. They use these organs, called proboscis, to siphon nectar.

“Most of the giant silk moths, such as the luna moth, only have vestigial mouthparts as adults and do not feed,” says Matthews.

“Hawk moths feed on foliage as caterpillars and are also active nectar feeders as adults. Some hawk moths have evolved especially long tongues to feed on flowers with similar length nectar spurs and in doing so pollen is transferred to their heads and carried to other plants of the same species.”

She points out that hawk moths with very long tongues can reach the nectar in flowers without their heads actually touching the part of the flower that contains pollen.

“So instead of being pollinators, these moths are robbing the nectar and not providing any service to the plant.”

Why Size Matters

Surprisingly, the newly discovered hawk moths are likely small because of their habitat. Typically, island ecosystems are known for creatures that are bigger than their mainland counterparts. For example, consider giant tortoises on the Galapagos Islands and Komodo dragons, found on some islands in Indonesia.

But some insect species in the Bahamas are smaller than their relatives. That’s the case for some butterflies found in the area.

“In environments where resources such as caterpillar food plants are limited, being smaller and thus requiring less food is an advantage for survival of a species,” says Matthews. “Land area supporting caterpillar host plants is limited on small islands and rainfall, though heavy at times, is scarce for most of the year in the Bahamas, thus caterpillar food plants, and adult nectar plants can be very limited at times.”

She says the size of the three new species is striking compared to similar insects, but not surprising because other species in the same genus are also small.

It’s also compelling news because it’s fascinating when previously unrecognized species are uncovered.

“Our study shows that even in such a popular group of moths (hawk moths) there are still new species to be discovered,” Matthews says. “It is especially important to know and be able to recognize the fauna of vulnerable habitats.”

These three species only occur in the Bahamas or Lucayan Archipelago. And one is only known to exist on a small island.

“Along with providing ecosystem services such as pollinating plants and providing food to birds and other vertebrates, butterflies and moths are of educational and ecotourism interest and thus a natural resource to be studied and appreciated.”