Encyclopedia of Biology

motor unit A single motor neuron and the entire
complement of muscle cells that receive synaptic con-
nections from it.

MPF(M-phase promoting factor) A protein complex

containing cyclin and a cyclin-dependent protein kinase

that triggers a cell to enter mitosis (M phase). Cyclin B

230 motor unit

occasional pest in nurseries, where it would take only one

or two of the huge caterpillars to defoliate a small sapling.

Whether the long-standing association between moths

andhumans will continue into the next several centuries is

as uncertain as the future of the human species. People

continue to alter the Earth in ways detrimental to other

species and to ourselves. Very likely the salvation of wild

silk moths lies with that segment of the human population

that cherishes the moths’ existence and keeps the knowl-

edge of their intriguing, mysterious ways.

—James G. (Spider) Barbour,

a field biologist specializing in entomology

and ecology, has 25 years of field experience

in the Hudson Valley, especially in the

Catskills, Hudson Highlands, and

Westchester County. He conducts botanical,

rare species, wetland, plant community,

and insect surveys. He and his wife, Anita, are

the authors of Wild Flora of the Northeast.

Silk Degrees: A Tale of Moths and People,

Part Two

(continued)

Scalar patterning of a butterfly’s wing magnified ×96. Note the shinglelike pattern of the wing, which promotes heightened aerodynamic
lift during the insect’s flight.(Courtesy of Janice Carr, Centers for Disease Control and Prevention)