Striking silk moths


The past two weeks have produced encounters with two beautiful female silk moths, both members of the family Saturniidae, which contains approximately 1,300 species. That beauty will be brief, as each will typically experience a lifespan of one to two weeks. Neither adult moth will ever feed, due to their shared characteristic of reduced or undeveloped mouth parts.

The larger of the two, the Polyphemus moth (Antheraea polyphemus) is typically tan in color, with an average wingspan of six inches. One of its most effective defense mechanisms, which helps to protect it from predators, is the presence of large eyespots set within a pattern said to resemble that found on the head of the great horned owl.

Both species lay eggs on the leaves of various host plants. When the eggs hatch, small caterpillars emerge and feed heavily before spinning silken cocoons. Larvae feed on the leaves of host plants such as sassafras, birch, oak, willow, beech, hickory, maple, ash, cherry, apple and tulip trees. The caterpillar of the Polyphemus moth can eat 86,000 times its weight at emergence in less than two months.

The smaller Promethea moth (Callosamia promethea), also commonly called the spicebush silkmoth due to its preference for that shrub as a common host species, has a wingspan of three to four inches. Females are rust and cream-colored. They release pheromones to attract males at specific “calling times” in the late afternoon and early evening. Some females are polyandrous, meaning they will mate with multiple males, and are the only moths in the family Saturniidae known to do so.


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