The Fig Sphinx Moth: A New Bermuda Resident

In the Winter Edition of Envirotalk, Department Of Environment & Natural Resources Entomologist Claire Jessey highlights the Fig Sphinx moth, which is apparently a new resident of the island.

In the report, Ms. Jessey said, “In October 2017, a large and unfamiliar moth was presented to the Department of Environment and Natural Resources for identification. After a little research, it was identified as Pachylia ficus, the Fig Sphinx moth.

“This moth was not previously recorded in Bermuda and so its unexpected presence was duly noted as a random and unexplained occurrence – possibly as a sole migrant blown off course – and documented for the natural history records with no expectation of seeing another. However, over the next several months, specimens of the same moth were reported periodically from several locations island wide. About every four or five months another adult moth would be submitted for identification.

“Specimens were collected, preserved, pinned and stored in the island’s insect collections at BAMZ and the Department of Environment and Natural Resources.

Pachylia ficus adult [Photo: Tommy Sinclair October 2017]:

“An exceptionally large moth such as this one, has an accordingly large larval stage [caterpillar] and based on the number of adult moths appearing over this extended period of time, it did suggest that there was now an established population of these moths on the island.

“It would only be a matter of time therefore until the caterpillar was noticed and submitted for identification. However, it was not until many months later that an image of the larva was sent to this Department for identification. The distinctive appearance made it easy to confirm that it was the same Pachylia ficus species.

“Although the plant host species was known from scientific information available online, there was no confirmation of the caterpillar actually feeding on or being associated with the suspected host plants in Bermuda. Until, surprisingly, several large and distinctive droppings [frass] were found outside at the author’s residence. This frass was a crucial clue to the active feeding of a large caterpillar nearby.

“Investigation revealed one large caterpillar of the Fig Sphinx feeding on an Indian laurel [Ficus microcarpa] seedling growing out of a Bermuda stone wall. This final piece of evidence confirmed that Pachylia ficus was a new resident of the island, capable of surviving on Indian Laurel host plants, of which Bermuda has plenty, and presumably breeding and producing the multiple generations seen over the preceding months.

“Pachylia ficus is a member of the Sphingidae family of moths which are commonly referred to as Hawk Moths, Sphinx Moths and Hornworms. This family contains some of the largest recorded moths in the world and they are known for their agile and sustained flying ability, similar to that of hummingbirds.

“The Fig Sphinx caterpillar feeds on hosts in the Moraceae family which includes ornamental ficus, the Indian laurel and edible fig trees. Mango [Mangifera] and breadfruit [Artocarpus] trees within the Moraceae family are also recorded as occasional hosts.

“The caterpillars are large and have several different colour forms [called morphs] and are often well camouflaged in the foliage in which they feed. They often pose as motionless stems or twigs during the day, becoming active at night and feeding voraciously on the leaves of their host plants.

“The young caterpillar is often uniformly bright green, turning mottled brown, beige and white as it develops, and changing to a striking teal and orange colour combination just prior to pupation into the adult moth.

“Pupation takes place in a silken cocoon on the ground in the leaf litter not far from the host trees. The adult moth that emerges after approximately 22 days is bulky and large, with a wingspan of 4 ½ to 5 ½ across with a mottled olive green and drab brown appearance with white wing spots at the tip of the leading edge of each forewing.

“The adult moths fly at dusk, feeding on the nectar of flowers with their long proboscis [straw like mouthparts]. The adults are often attracted to artificial lights and found resting on the sides of buildings.

“How this moth ended up in Bermuda is still a mystery. Ficus plants have not been imported through the Department of Environment and Natural Resources for at least ten years, so it has not entered unnoticed as eggs on a plant in this way.

“However, if a plant was smuggled into the island to circumvent the strict entry requirements, it is possible. This activity is illegal and puts the entire island at risk of hitchhiking pests that can be devastating for our natural environment.

“The natural range of Fig Sphinx moths is throughout Central and South America, the West Indies, Florida and Texas. The moth has been recorded venturing as far as 1,000km or more away from its natural range. These large moths are considered to be long distance migrants and strong fliers.

“It is possible that storm winds may have blown several of these moths [or possibly just one gravid [pregnant] female] off course and they managed to survive the long journey, as unusual as that seems.

“A similar occurrence with migrating Monarch butterflies was recorded in 1970 by Dr. Walwyn Hughes, Director of the Department of Agriculture at the time. He photographed a large number of Monarch butterflies flying in towards the island over the water from the north and landing on casuarina trees in Ferry Reach.

“Similar sightings were noted in other years, particularly in the months of September and October. It was proposed that these sightings were associated with the passage of swiftly moving cold fronts. Other sightings were of flocks of Monarchs leaving Bermuda in those same months heading south at wave top level from several locations on the island on their way to some unknown destination. Just as migratory birds can make their way to our small island, so too can these larger moths.

“Occasional visitors have included the Black Witch moth [Ascalapha odorata] and the Death’s-Head Hawk moth [Achrontia atropoes]. Mimic butterflies [Hypolimnas missipus], Painted Ladies [Vanessa cardui] and Red Admirals [Vanessa atalanta], although smaller, are just some of the butterflies that have survived the long flight to Bermuda to grace us with their presence. Unlike many of the visiting moths and butterflies, the Fig Sphinx moth has decided to take up residence with us.”

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Category: All, Environment, News