Flora and Fauna News

Sonoran Desert Edition

Sunday, Apr. 13, 2008
Vol. 11 No. 7

Giant Swallowtails
On The Wing

By Michael Plagens
Sonoran Desert Sciences


PHOENIX, Az. ----- Butterflies and springtime go together. Vying as the largest of Arizona butterflies, Giant Swallowtails (Papilio cresphontes) have recently eclosed (hatched) from their overwintering chrysalides and are now flitting through urban neighborhoods and citrus groves. They are avid flower visitors, coming to Lantana, Butterfly Bush (Buddleya), and Caesalpinia. The male butterflies, when not taking nectar, are on patrol for females which they might encounter near the flowers or else near citrus trees. The females on the other hand search neighborhoods for citrus trees suitable for egg laying. The April emergence coincides with the flush of new tender citrus leaves.

Giant Swallowtail caterpillars use the leaves of citrus trees (orange, grapefruit, lemon) where they employ quite a trick to avoid getting eaten by birds: They appear to be a freshly deposited bird dropping! It does not always work as mockingbirds often detect the caterpillars despite the disguise and eat them. Many more caterpillars and eggs are taken by predators (e.g. spiders, assassin bugs, lace wings) and parasites. The urban gardener might be distressed to see big chunks of leaves eaten away and decide to spray the plants with toxic chemicals. All but the most sickly trees can withstand huge numbers of caterpillars, so really the trees are not at all at risk. Furthermore, by spraying, the unnoticed predators and parasites will be destroyed as well, allowing for a population explosion of caterpillars plus other secondary pests like scales and mites, that will prompt even more toxic sprays. This "pesticide treadmill" will harm the birds as well as your own environment. So, why not just let there be Butterflies!

The Two-tailed Swallowtail, also found in Arizona, often has a slightly wider wingspan. It is found in deep canyons where ash trees grow.

Tan Moths
In the House

PHOENIX, Az. ----- Yet another insect, this time a moth, has been emerging from cocoons. The adult moths are often found fluttering against windows on the inside of homes! The mature caterpillars found their way into houses the previous summer after dropping to the ground from high in Washington Fan Palms and then searching for a suitable place to make their cocoons. The caterpillars are attracted to the thick fibers of carpeting and there spin a tough coccon of silk and chewed up carpet bits. The moth is appropriately named the Palm Flower Moth because they feed in the dense flowering stalks of these widely planted trees. The caterpillars are pink and are a favorite food of Gila Woodpeckers and Northern Mockingbirds. Read more on Bug Eric.s Blog

Giant Swallowtail Butterfly (Papilio cresphontes).
Photo by Bruce Walsh - Arizona Butterflies.

The "Orange Dog", common name for the larva of the Giant Swallowtail.
Photo by Bruce Walsh - Arizona Butterflies.

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Palm Flower Moth (Litoprosopus coachella).
Photo by Bruce Walsh - Moths of Southeast Arizona.

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Flora and Fauna News appears several times
per month and provides current information about the birds, insects and plants
(natural history) living in the Arizona Sonoran Desert.
Copyright Michael J. Plagens, 2008
Send questions or comments to mjplagens@arizonensis.org