Hummingbird moths go through a complete metamorphosis during their life cycle, with four distinct stages: egg, larva (caterpillar), pupa (chrysalis), and adult. The larval or caterpillar stage is when the most dramatic changes in appearance occur as the moth develops from a tiny newborn to a fully grown caterpillar ready to form its chrysalis.
Appearance of Newly Hatched Caterpillars
Hummingbird moth caterpillars hatch from small, round eggs laid singly on host plants by the adult female moths. When newly emerged, the tiny larvae are only a few millimeters long. They often have a reddish-brown or greenish-brown coloration with a black head capsule. The body may be covered in fine hairs. As they moult and grow, the caterpillars develop distinct striping and other markings.
Size and Growth
Over 2-6 weeks, hummingbird moth caterpillars go through 5-6 larval instars, shedding their exoskeleton and increasing dramatically in size during each one. Fully grown caterpillars reach 1.5-2 inches (4-5 cm) in length. Early instars are tiny, while fifth and sixth instars are much more substantial and bulky.
Growth rates can vary based on environmental factors like temperature and food availability. Caterpillars may grow faster and reach a bigger ultimate size when food is plentiful. Cool temperatures can slow development.
Body Shape and Segments
Hummingbird moth caterpillars have a typical caterpillar body shape with a head capsule followed by a long, cylindrical body made up of sections called prolegs toward the rear. The body is covered in fine hairs (setae). As the caterpillars grow through successive molts, the body begins to thicken and expand in preparation for pupation.
Color Patterns
There is considerable variation in the exact colors and patterns on hummingbird moth caterpillars based on the different species. Some common traits include:
- Creamy white, yellow, green, brown, or black background coloration.
- Distinctive stripes running the length of the body.
- White or cream diagonal lines along the sides.
- Black, orange, or red spots circled in white, yellow, or cream.
- A brown or black head capsule.
Prominent hornlike tubercles may protrude from the body segments. These are often reddish or pinkish in color. There may also be color variations between instars, with caterpillars becoming more vibrantly patterned in later development.
Identification Features of Species
Some features that can help identify the specific species of hummingbird moth caterpillar include:
Tobacco Hornworm (Manduca sexta)
- Large size, up to 4 inches long
- Distinctive red horn rising from the rear
- Seven white stripes on a green background
- Black and orange spots circled in white
Tomato Hornworm (Manduca quinquemaculata)
- Blue-green color
- Seven white V-shaped markings along the sides
- No spots
- Red or orange head
Virginia Creeper Sphinx (Darapsa myron)
- Pattern of black, yellow and cream markings
- Black head capsule with white markings
- Red patch on rear
- Prominent curved horn on rear
Hummingbird Clearwing (Hemaris thysbe)
- Green color
- Broken yellow lines along back and sides
- Rows of black dots
- Red head
Snowberry Clearwing (Hemaris diffinis)
- Greenish-brown background
- Dark stripe along the back
- Row of seven yellow-orange spots on each side
- Red head capsule
Bumblebee Clearwing (Hemaris fuciformis)
- Plump, almost slug-like shape
- Velvety black color
- Rows of orange-yellow dots
- Thin white lines along the sides
Behavior and Movement
Hummingbird moth caterpillars are active feeders. They can voraciously consume plant leaves, flowers, and stems. Some behavioral traits include:
- Wriggling motions as they move along branches
- Rearing up into vertical S-shaped postures if disturbed
- Quick dropping behavior if they fall off a plant
- Hiding under leaves or in leaf shelters during rest periods
Later instar caterpillars are sluggish compared to the speedy movements of younger ones. They may leave the host plant to pupate in a sheltered spot on the ground or debris.
Host Plants
Hummingbird moth caterpillars have preferred host plants they feed on. These vary by species and can include:
- Tomatoes, tobacco, potatoes, peppers (hornworms)
- Viburnum, honeysuckle, snowberry (clearwings)
- Virginia creeper, grapes (Virginia creeper sphinx)
Caterpillars often rest on the underside of leaves or hide inside shelters they construct by rolling and tying leaves with silk.
Defensive Adaptations
Hummingbird moth caterpillars have some adaptations that may help deter predators, including:
- Camouflage coloring to blend in with host plants
- Irritating spines or tubercles containing toxic chemicals
- Ability to regurgitate foul-tasting fluids when disturbed
- Dropping behavior when startled to avoid attack
Some species closely resemble bird droppings in appearance, which likely offers protection. Caterpillars may thrash violently if touched.
Pupation
When fully mature, the caterpillar will stop feeding and enter the pupal stage. It crawls down the host plant and finds a sheltered spot on the ground, leaf litter, or a crevice in bark or rocks. There it sheds its final larval exoskeleton to reveal the pupa underneath.
The pupa is oval in shape and may be orange, brown or black in color with a hardened shell. The future adult moth develops inside the pupal case over a period of 1-2 weeks or longer before it emerges as the winged adult stage.
Conclusion
Hummingbird moth caterpillars go through a series of growth phases called instars as they develop from tiny hatchlings to plump, inch-long larvae. Distinctive hornlike tubercles, vivid stripes and spots, and wriggling movements characterize these nectar-feeding moths during their vegetarian larval phase. Knowing what to look for can help identify hummingbird moth species by their caterpillars.
