Glossary of terms

Chorion: < kor ‘ e – on> Another name for the egg shell.

Compound eye: A large grouping of light gathering organs that allow the insect to detect color and motion. For most insects, resolution is not very good.

Diapause: A period of delayed development or growth accompanied by reduced metabolism and inactivity.

Diet: Another word for the cube of food the insect feeds on.

Dorsal vessel: The part of the insect heart that contains valves and chambers.

Ecdysis:  The process of shedding of the old exoskeleton.

Frass: Another term for larval insect droppings or excretion.

Horn: A long spiked projection from the rear of the larva. It may serve as camouflage. Although all Manduca emerge with the horn, many loose it during larval life. Sometimes its referred to as the dorsal horn.

Instar: The insect at the various times during larval development.

Larva: The immature form of an insect that follows the egg stage. Larva is the singular form, larvae is plural.

Mandible: The chewing structures of the insect mouth.

Manduca sexta : The scientific name for the Tobacco Hornworm. Sexta refers to the six yellow spots on each side of the adult abdomen.

Metamorphosis: A change in form, structure or function as a result of development; specifically the physical transformation undergone by various animals during development after the embryonic state, as of the larva or an insect to the pupa, and the pupa to the adult.

Molt: A process that involves the building of a new exoskeleton and the casting off of the old exoskeleton.

Ocelli: <o – cel – li> Larval light detecting organs. There are usually 5 or 6 ocelli around the edge of the mandibles. These are tiny dark spots forming a semi-circle.

Proleg: The stubby, fleshy limbs attached to the abdomen of certain insect larvae, as in caterpillars. Manduca larvae have four pairs of prolegs on the abdomen, with an additional pair at the very last segment.

Pupa: A non-feeding stage of development between the last larval and adult forms, characterized by many anatomical changes and, often, by enclosure in a cell or cocoon. Pupa is the singular form, pupae is plural.

Spiracle: <spear – a – cul> An opening in the body wall used for breathing. Its analogous to our nose. In Manduca, they are found on the sides of certain thoracic and abdominal segments. Internally, the connect to trachea.

Stage: Refers to a life period. In Manduca there are four stages, egg, larva, pupa and adult.

True legs: legs found on the thoracic segments of the larva. These legs are segmented and very different from the prolegs of the abdomen.