Out of the blue

Butterfly experts aflutter over arrival of foreign species at Dead Sea

Western pygmy blue, native to Americas, has made its home in the Persian Gulf over last 30 years. Nobody knows how specimens, first spotted a week ago, reached Israel

Sue Surkes is The Times of Israel's environment reporter.

A pygmy blue butterfly (Brephidium exilis thompsoni) on sea purslane, Sesuvium portulacastrum, in Grand Cayman, Cayman Islands. (Charles J. Sharp/Wikimedia Commons, CC BY-SA 4.0)
A pygmy blue butterfly (Brephidium exilis thompsoni) on sea purslane, Sesuvium portulacastrum, in Grand Cayman, Cayman Islands. (Charles J. Sharp/Wikimedia Commons, CC BY-SA 4.0)

Butterfly enthusiasts and lepidopterists are in a flutter over the sudden appearance around the Dead Sea of a species called the western pygmy blue (Brephidium exilis), the smallest butterfly in North America, which in recent years has also made its home along the Persian Gulf.

Common in the southwestern United States, from California to west Texas, and from Mexico to Venezuela, the species first appeared in the United Arab Emirates in around 1990 and has since spread northward as far as Kuwait.

One theory is that it arrived in the UAE at the time in the form of eggs on a specimen of sesuvium, a succulent desert plant that someone connected to the US State Department may have taken to plant in the desert kingdom as a reminder of home.

Sesuvium, known as sea purslane, a species of which also grows wild in the UAE, is a popular host plant for the western pygmy blue, meaning the butterfly likes to lay its eggs on it. But it will also do so on other kinds of desert plants, species of which are present in the US, the Persian Gulf and in Israel’s deserts. These include suada, or sea blites, nitraria and salt bush (atriplex).

A western pygmy blue — the blue appears on the inside of the male’s wings — was first reported in Israel on August 3 by a butterfly enthusiast vacationing at a Dead Sea hotel. It was perched on a sesuvium plant in the hotel’s garden.

According to Dr. Oz Ben-Yehuda, a leading member of the Israel Butterfly Association who lectures on zoology, ecology and evolution at two academic institutions, nobody knows how it got there. But with conditions in the Dead Sea area ideal for it, it is already flourishing.

“Did somebody travel in the UAE and bring it back? Could it have come from the US? We don’t know,” he said. “It’s hard to believe that one of them flew over the whole of Saudi Arabia and Jordan and got here and laid eggs.”

Israel is home to roughly 140 butterfly species.

According to Ben-Yehuda, the newcomer is only the third species to enter the country from foreign climes.

One came and then disappeared, while another — the Geranium bronze (Cacyreus marshalli) crossed from Africa into Spain, slowly established itself across Europe and entered Israel around two years ago, possibly from Turkey. No reports of damage to the local ecosystem have been received either for the western pygmy blue in the Persian Gulf nor for the Geranium bronze, which is now established in Israel.

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