Hummingbird moths are fascinating insects that get their name from their ability to hover and feed on flower nectar just like hummingbirds. While the adults are well-known for their winged beauty and aerial acrobatics, the larvae of hummingbird moths are intriguing in their own right. So what does the larvae of a hummingbird moth look like?
The larvae, also known as caterpillars, have a very distinctive appearance that helps them blend into their environment and avoid predators. When fully grown, the caterpillars are around 2 inches long. They have plump green or brown bodies with white or yellow stripes running down their backs. The stripes provide camouflage by breaking up the caterpillar’s outline among the stems and leaves of the host plants they feed on.
Some key features that help identify hummingbird moth caterpillars include:
Head
– Large, round head that can be retracted into the body for protection
– Powerful chewing mouthparts for eating leaves
– Simple eyes (ocelli) to detect light
Body
– Long cylindrical body composed of segments
– Covered in setae (short hairs) that help camouflage it
– Rear end has a horn or tail to deter predators
– Prolegs on abdomen to help grip and climb plants
Color and Markings
– Green, brown, or yellowish main body color
– Paler yellow, white, or green stripes running lengthwise
– Dots, chevrons, or other patterns on the sides for camouflage
Hummingbird moth caterpillars go through several growth stages called instars as they eat and grow. With each successive molt, the caterpillar increases in size and becomes more vividly patterned. When fully mature, they reach an impressive size compared to other caterpillars.
Life Cycle and Habits
To better understand the appearance of hummingbird moth caterpillars, it helps to look at their life cycle:
Eggs
– Laid singly on the underside of leaves of host plants
– Tiny, round, greenish or white eggs
– Hatch within 4-10 days
Larvae
– Emerging larvae immediately start feeding and growing
– Molt and increase in size through 5 instars over 2-6 weeks
– Feast on leaves of host plants including tomato, tobacco, apple trees
– Well camouflaged; hide during the day
Pupa
– Form a chrysalis attached to a stem or leaf
– Undergo metamorphosis over 1-2 weeks
Adult
– Emerge from the pupa fully formed
– Live for around 5 weeks
– Visits flowers during the day to drink nectar
The caterpillars are voracious eaters and typically come out at night to feed on leaves. During the day, they rest camouflaged along twigs and stems. If threatened, they will rear up and wave their head from side to side to scare off potential predators. Their striped appearance helps them disappear among leaves and vegetation.
Identification
There are over 1,200 species of hummingbird moths in the Sphingidae family. Here are some common species and how to identify their larvae:
Tobacco hornworm
– Most common species
– Large, green caterpillar with white lines
– Prominent horn on rear end
Tomato hornworm
– Closely related to tobacco hornworm
– Green, with V-shaped markings and no horn
– Damages tomato, potato, and pepper plants
Hummingbird clearwing
– Yellow-green with faint stripe on back
– Black head with white dots on face
– Feeds on honeysuckle, viburnum, and related plants
Snowberry clearwing
– Broad green body with yellow side stripes
– Black legs and prolegs
– Eats snowberry, ash, currants, and other plants
Growth and Development
The growth of a hummingbird moth caterpillar can be categorized into five larval instars. Each stage is separated by a molting event where the caterpillar sheds its old exoskeleton and emerges larger with new skin. Here is an overview of the instars:
Instar 1
– Length: 2-5 mm
– Body: Yellowish or translucent after hatching
– Markings: Few markings
– Duration: 4-5 days
Instar 2
– Length: 5-10 mm
– Body: Base color establishes as green or brown
– Markings: Faint lines appear
– Duration: 3-4 days
Instar 3
– Length: 10-20 mm
– Body: Bright base color, markings more defined
– Markings: Distinct stripes visible
– Duration: 4-5 days
Instar 4
– Length: 20-35 mm
– Body: Larger, vividly colored
– Markings: Stripes and patterns stand out
– Duration: 5-6 days
Instar 5
– Length: 30-50 mm when mature
– Body: Very plump and large
– Markings: Clear striping helps camouflage
– Duration: 8-10 days
After the fifth instar, the fully grown caterpillar stops eating and searches for a pupation site. This marks the end of the larval stage as it transitions into a pupa and undergoes metamorphosis.
Defense and Camouflage
Hummingbird moth caterpillars have a variety of physical and behavioral adaptations to help them survive the two or more weeks they spend feeding in the larval stage.
Camouflage
– Disruptive striping and markings conceal shape
– Color blends into leaves, stems, and twigs
– Change appearance between instars
– Hide under leaves or near stems during day
Defensive Behavior
– Rear up and sway head if disturbed
– Regurgitate smelly fluid
– Drop from plants on silk strands to escape
– Change direction or stop moving to avoid notice
Morphological Features
– Spines and hairs cause irritation if eaten
– Retractable head can be tucked into body
– Rear horn deters predators
– Bright warning colors in later instars
These adaptations make the larvae well-suited to feed and grow safely in their natural surroundings. The cryptic appearance hides them from predators like birds, wasps, and spiders during their vulnerable juvenile stage.
Pupation
When the caterpillar reaches full maturity after 2-6 weeks of feeding and growing, it will leave the food plant and begin wandering in search of a suitable pupation site. This marks the transition from the larval to the pupal stage.
Pupation Behaviors
– Crawls down from host plant to ground, stems
– Spins button of silk to attach abdomen to substrate
– Sheds larval skin, revealing pupa underneath
Pupa Characteristics
– Brown, black, or green camouflaged casing
– Short, thick body with wing pads visible
– Attached by cremaster spines or silk strand
– Immobile pupa does not feed
Pupal Duration
– Pupates for 1-2 weeks in summer
– May overwinter as pupa to emerge in spring
– Adult moth emerges by splitting pupal case
The pupa is the intermediate stage between larva and adult. It metamorphizes into the winged adult form before the moth emerges to continue the lifecycle.
Threats and Mortality
While they have good camouflage, hummingbird moth caterpillars still face many threats during their larval development:
Predators
– Birds – chickadees, cuckoos, orioles
– Wasps – parasitic braconid and ichneumon wasps
– Spiders – orb weavers, jumping spiders
– Lizards, frogs, and toads will eat caterpillars
Weather Events
– Late spring frost can kill young larvae
– Excess heat causes desiccation
– Drowning during heavy rains
Diseases and Parasites
– Baculoviruses – cause fatal infections
– Fly and wasp maggots as internal parasites
– Nematode worms can infect larvae
– Bacterial diseases from species like Serratia
Mortality Rates
– Up to 95% don’t complete development
– Average 15-20% survival to adulthood
– Likely higher mortality in first few instars
Despite their well-developed defenses and adaptations, relatively few hummingbird moth larvae will survive to become pupae and adults. However, the high reproductive rate ensures the species continues successfully generation after generation.
Conclusion
In summary, hummingbird moth larvae have a distinctive striped or banded appearance in shades of green, brown, yellow, and white that helps conceal them among leaves and stems. The caterpillars develop through five larval instars over 2-6 weeks, molting and growing between each stage. Camouflage, warning colors, and defensive behaviors protect the larvae from predators as they feed voraciously on the leaves of host plants. If they successfully pupate, the caterpillar transforms into the winged adult moth inside the chrysalis. Hummingbird moth larvae play an important ecological role during their short lives, helping maintain balance in the natural communities where they live. Their unique characteristics and habits are part of the remarkable diversity of lepidopteran insects.
