Silken Spikes

What am I looking at?

This is a caterpillar of the calleta silkmoth (Eupackardia calleta) just before it pupates. You can see the defensive spiked spheres on its back (1) and the very top of its head. 

Click on the right arrow to see the strikingly dark adult moth.

Biology in the background

These moths live in the American Southwest and Central America. The caterpillars feed mainly on the leaves of ash trees and several varieties of desert and scrubland shrubs – but in captivity they can be reared on privet shrubs.

During the first few weeks after they hatch, the caterpillars are gregarious, staying together and feeding as a group. As they grow, however, they become solitary and feed alone. The adult moths emerge in the fall or spring and spend most of their time searching for a mate. Interestingly, the males are diurnal (active during the day), while the females are nocturnal (active at night). Therefore, they mate during their overlapping periods of activity around dawn or dusk.

These caterpillars show aposematic coloration (a dramatic pattern to warn off predators) – in this case, wavy black and green markings with red accents and spiky blue tubercles. When they’re disturbed, these caterpillars secrete defensive chemical protection – a milky white, mildly toxic solution – from their tubercles.  

These caterpillars can grow up to 60 millimeters long, or roughly three times larger than a human thumbnail. The adult moths can have a wingspan of up to 11 centimeters long, or roughly the length of a human palm.

Technique

These images were created using macrophotography.