Life Cycle: Eggs, Larvae, Pupae, Eclosion

An understanding of the life cycle and general biology of lepidoptera adds much to the overall experience of moth photography. There is an excellent on-line syllabus and illustrated Entomology Tutotial Series offered by North Carolina State University. This is a fine resource for your use in finding answers to many puzzling questions about the insects you encounter. I thank Professor John R. Meyer in the Deptartment of Entomology there for permission to reproduce below a portion of the chapter dealing with holometabolous development.

Holometabolous insects have immature forms (larvae) that are very different from adults. Larvae are "feeding machines", adapted mostly for consuming food and growing in size.  They become larger at each molt but do not acquire any adult-like characteristics. When fully grown, larvae molt to an immobile pupal stage and undergo a complete transformation. Larval organs and appendages are broken down (digested internally) and replaced with new adult structures that grow from imaginal discs, clusters of undifferentiated (embryonic) tissue that form during embryogenesis but remain dormant throughout the larval instars. The adult stage, which usually bears wings, is mainly adapted for dispersal and reproduction.

Appearance Larval Type Common Name Description Examples
Body cylindrical with short thoracic legs and 2-10 pairs of fleshy abdominal prolegs Butterflies and Moths
Body fleshy, worm-like.   No head capsule or walking legs House fly, flesh fly
Appearance Pupal Type Common Name Description Examples
Developing appendages (antennae, wings, legs, etc.) held tightly against the body by a shell-like casing.   Often found enclosed within a silken cocoon. Butterflies and moths
Body encased within the hard exoskeleton of the next-to-last larval instar Flies
Holometabolous Development data from ENT 425 Tutotial Series at NC State University Professor John R. Meyer, Dept. of Entomology

Imperial Moth - Eacles imperialis
just laid - Robert Patterson
Royal Walnut Moth, Citheronia regalis
ready to hatch - Troy Bartlett
Io Moth - Automeris io
just eclosed - Alan Chin-Lee
Polyphemus - Antheraea polyphemus
Jim Kennedy

Eggs, depending upon species, vary in number, size, shape and coloration. You'd need a magnifying glass to examine eggs of many moths. Larger species such as some of the Giant Silkmoths may have eggs several mm in diameter. Eggs may be laid singly or in masses of 100 or more. There is usually a high degree of synchrony in the hatching of a clutch of eggs (taking from a few days or weeks to several months in the case of species who overwinter in the egg stage). At eclosion or hatching the egg remains are usually eaten by the first instar larvae.

  Larvae or Caterpillar Stage
Imperial Moth - Eacles imperialis
1st instar - Stuart Schwartz
Imperial Moth - Eacles imperialis
early 5th instar - Stuart Schwartz
Luna Moth - Actias luna
color forms - Stuart Schwartz
Io Moth - Automeris io
group behavior - Machele White

Larvae may go through four, five (usually) or more instars during development. This may require several weeks or months and even several years in a few cases. Coloration and markings may change significantly from instar to instar. In some species there may be distinctive color forms in the larvae even when they originate from the same egg mass/parentage.

Royal Walnut Moth - Citheronia regalis
early instar - Troy Bartlett
Royal Walnut Moth - Citheronia regalis
intermediate instar - Troy Bartlett
Royal Walnut Moth - Citheronia regalis
late instar - Troy Bartlett

5-spotted Hawkmoth - Manduca quinquemaculata
black form - Jim McClarin
5-spotted Hawkmoth - Manduca quinquemaculata
green form - Janice Stiefel
5-spotted Hawkmoth - Manduca quinquemaculata
black form - Bryan Reynolds

  Cocoon and Pupa/Chrysalis
a. - Joyce Gross b. - Pete Ganzel c. - Charles Lewallen d. - John Himmelman

  1.  Cocoon containing corpse of a Western Tussock Moth pupa and, beside it, the puparium of a parasitoid Tachinid Fly.
  2.  A well crafted silk cocoon of the Cecropia Moth, Hyalophora cecropia.
  3.  A Bagworm Moth case used for protection during the larval phase, it serves also as a pupation site. Wingless females never leave the  case. In this instance a male has eclosed to adulthood leaving behind the puparium or exuvium now projecting from the tip of the case. It  will locate a female when she releases a pheromone attractant, and mate with her through a small opening in her protective case.
  4.  Numerous micromoths are known as casebearing moths and utilize diversely designed cases in which to pupate. This is the Pistol  Casebearer Moth, Coleophora atromarginata, named after the shape of its case.

e. - Machele White f. - Machele White g. - Machele White h. - Machele White
  1.  Cocoon of the Southern Tussock Moth, Dasychira meridionalis, richly lined with the caterpillar's hairs added to the silken enclosure.
  2.  Wingless female of the Live Oak Tussock Moth, Orgyia detrita with her eggs on top of the cocoon from which she eclosed. Here we have  three life stages in a single photo. She will probably cover the egg mass with a frothy protective coating.
  3.  Some species use little or no silk to conceal their pupation site, especially when it is their custom to pupate in leaf litter. This is the  Bella Moth, classified here as part of the complex species Utetheisa ornatrix.
  4.  Frequently, skin of the last instar caterpillar is found in the cocoon with the pupa. In this case the caterpillar of a Giant Leopard Moth,  Hypercompe scribonia did not incorporate its body hairs into the cocoon. The brown puparium seen here will blacken prior to eclosure.

i. - Tim Dyson - Sphinx kalmiae j. - Alan Chin-Lee - Manduca rustica k. - Alan Chin-Lee - Erinnyis ello
  1.   Pupae Jewels found in leaf litter. Laurel Shinx Moth in Ontario.
  2.   Rustic Sphinx Moth in Florida.
  3.   Ello Sphinx Moth in Florida.

MothTalk/MothTalk020.htm -- 01/15/2007