Tiger moths, belonging to the brightly colored Arctiinae subfamily, are recognized for their striking patterns, which often serve as a warning to potential predators. The dietary habits of this insect group differ dramatically across its life stages. The larval stage, commonly known as the “Woolly Bear” caterpillar, is the primary consumer, focusing on gathering nutrients for growth and metamorphosis. In contrast, the adult moth stage feeds minimally, relying heavily on the energy reserves accumulated during its earlier life.
Larval Diet and Host Plants
The caterpillar stage is broadly polyphagous, meaning the larvae consume a wide variety of plants rather than specializing on a single host. Their primary objective during this phase is the rapid accumulation of energy, stored as fat, which fuels the transformation into the adult moth. This need for substantial energy drives them to feed on many common, low-growing plants and weeds.
Specific host plants include dandelions, clover, plantain, dock, and nettles. This generalist approach allows them to thrive in diverse environments, from gardens to open fields. The larvae possess strong mandibles designed to process this solid plant material efficiently.
These caterpillars feed and grow before searching for a suitable place to pupate. The energy stored determines the success of their metamorphosis and the reproductive fitness of the resulting adult moth. For some species, the larval diet also involves acquiring chemical compounds that offer protection later in life.
Adult Moth Feeding Habits
The adult tiger moth stage represents a shift in dietary focus, moving away from heavy consumption and toward reproduction. Many adult tiger moth species feed very little, or not at all, subsisting entirely on the fat reserves they stockpiled as larvae. Their short adult lifespan is primarily dedicated to mating and egg-laying.
For the species that do feed, their diet consists of liquid energy sources, most notably nectar from flowers. Nectar provides the necessary sugars to power flight, which is crucial for finding mates and suitable egg-laying locations. The moths use a long, straw-like proboscis to sip this sugary liquid.
Beyond nectar, adult tiger moths also engage in “mud-puddling,” where they congregate to drink moisture from damp soil or puddles. This practice is not for energy but for mineral consumption, specifically sodium and other trace elements. These acquired salts are important for male moths, who can transfer them to the female during mating to improve the viability of their eggs.
Dietary Link to Chemical Defenses
A unique aspect of the tiger moth’s diet involves the sequestration of plant toxins, which provides a powerful chemical defense against predators. Certain larval species actively seek out and consume plants that contain toxic secondary metabolites, such as pyrrolizidine alkaloids (PAs). Plants containing PAs, like some species of rattlebox (Crotalaria), are targeted for their chemical content rather than just their nutritional value.
The tiger moth is able to tolerate these poisons, absorbing and storing them in specialized tissues throughout its body, a process called sequestration. These sequestered toxins are retained through the pupal stage and passed on to the adult moth, making the insect unpalatable to predators like birds. This chemical defense is often advertised by the moth’s bright colors, a warning signal known as aposematism.
These stored alkaloids have a dual purpose, as they are also used by male moths to produce sex pheromones. Males that have sequestered high levels of PAs use these compounds to attract females, sometimes transferring the defensive chemicals to the female during mating. This transfer provides the female and her eggs with a protective chemical shield, linking the larval diet directly to the reproductive success and survival of the next generation.