Glossary
The following definitions are for morphological and descriptive terms used primarily in larval descriptions. Most definitions are from Nichols (1989), Peterson (1962), or
Stehr (1987).
A
A: abdominal segment
Abdominal prolegs: all prolegs on any abdominal segment except the last, which are Anal prolegs
Adfrontal areas: an oblique sclerite on each side of the frons, usually extending from the base of the antennae to the epicranial suture where they meet,
or to the epicranial notch if they do not meet
Adfrontal setae: a pair of setae on the adfrontal areas, the more dorsal one being AF1
Adfrontal suture: the suture separating the adfrontal area from the cranium
Af: adfrontal setae
Anal comb: the mesal sclerotized prong ventrad of the anal plate and adjacent to the anus; used to eject frass
Anal fork: see Anal comb
Anal shield: the dorsal shieldlike covering of the last abdominal segment (= Anal plate)
Anal prolegs: prolegs on the last abdominal segment (A10)
Anterad: toward the front
Anterior: front; in front of
Anterodorsal: in front of and toward the back or upper part
Anteroventral: in front of and toward the venter or lower part
Apical: at the end or the tip
Approximate: close together
Armature: setae, spines, or sclerotized processes
Atrophied: rudimentary, reduced
B
Bifid: divided into two parts; forked
Bifurcate: forked; two-branched
Biordinal: crochets arranged in a single row of alternating lengths
Biserial: crochets with the bases arranged in two rows
Bisetose: two setae
Blades: thick flat spines on the proximolateral region of the hypophayngeal complex
C
Caterpillar: a larva with a conspicuous head, three pairs of thoracic legs, and prolegs; the larva of a butterfly, moth, sawfly, or scorpionfly (= eruciform)
Caudad: toward the posterior end or tail
Caudal: pertaining to the tail or posterior end
Cephalad: toward the head or anterior end
Cephalic: pertaining to the head; anterior
Chaetotaxy: the arrangement and nomenclature of setae (see Setal map)
Chalaza (Chalazae): a simple, sclerotized, elevated projection, usually bearing a single seta
Cleft: split or forked
Clypeus: the sclerite between the frons and the labrum
Condyle: a knoblike process forming part of an articulation by fitting into a depression
Crenulate: wavy or scalloped
Crochets: sclerotized, hooklike structures, usually arranged in rows or circles on the prolegs of Lepidoptera larvae
D
D: dorsal setae
Deciduous: having parts that may naturally fall off, be shed, or break away
Dentate: toothed
Distal: toward the tip or end; farthest from the body
Dorsad: toward the top or back
Dorsal: at the top or back or above
Dorsolateral: at the top and to the side
Dorsomesal: at the top and near the midline
E
Eclosion: hatching from the egg
Emarginate: with a dent or notch in the margin
Epicranial notch: the V-shaped dorsomedial space delimited laterally by the cranial halves
Epicranial suture: an inverted Y-shaped suture on face of head with arms diverging ventrad; the suture that separates the epicranial halves on the
dorsum of the head
Epicranium: the cranium above the frons
Epipharynx: inner surface of the labrum
Exuvia (Exuviae): the cast skin; typically used in describing the larval skin and pupal case
F
Filament: a long, slender structure
Filiform: hairlike or threadlike
Frass: the pelletlike excrement of caterpillars (and other insects)
Frons: medial sclerite on face of head delimited above by epicranial arms and below by frontoclypeal suture; sometimes termed frontal area (or front)
Front: the frons or frontal area (sometimes including the clypeus)
Frontal seta: a seta on the frons
Frontal suture: the two branches of the epicranial suture on either side of the frons
Frontoclypeal suture: the suture separating the frons from the clypeus
H
Hypopharynx: the median inner mouthpart structure anterior to the labium
Hypopharyngeal complex: a structure consisting of the Hypopharynx, Labial palpi, and Spinneret
I
Instar: the stage between molts
Integument: the outer body wall (epidermis + cuticle); the "skin"
L
L: lateral setae
Labial palpus (palpi): a pair of small, segmented sensory structures arising on the distolateral portions of the labium
Labium: the lower lip
Labrum: the upper lip
Larva (Larvae): the stages between the egg and pupa of those insects having complete metamorphosis
Laterad: toward the side, away from the midline
Lateral: to the side, or at the side of
Lateral penellipse: an incomplete circle of crochets closed laterally and open mesially
Looper: a caterpillar with some prolegs reduced or missing, usually on segments A3-5 (Geometridae) or A3-4 (Noctuidae)
M
Maxilla (Maxillae): the paired mouthparts posterior to the mandibles
Maxillary palp (palpi): a small, segmented sensory structure arising from the maxilla
Median: in the middle
Mesal penellipse: an incomplete circle of crochets closed mesally and open laterally
Meson: an imaginary vertical middle plane of the body
Mesoseries: a longitudinal row of crochets on the mesal side of a proleg; if curved, less than two-thirds of a circle
Mesothorax: the second thoracic segment
Metathorax: the third thoracic segment
Microspines: minute spines on the body, usually visible only under magnification
Monophagous: feeding on only one species
Multiordinal: crochets arising in a single row and in many alternating lengths
Multiserial: crochets arising in several rows
Multiserial circle: crochets arising in three or more concentric circles
N
Newcomer's organ: a dorsal gland on the seventh abdominal segment of late instar larvae that secretes honey dew on which ants feed
O
Ocellus (Ocelli): a simple eye of an adult insect (compare to Stemmata)
Ordinal: referring to the lengths of crochets (see Uniordinal, Biordinal, Triordinal)
Oviposit: to lay eggs
P
P: posterior setae
Penellipse: crochets arranged in an incomplete oval or circle (see Lateral penellipse, Mesal penellipse)
Penultimate: next to last
Peritreme: a sclerotized ring surrounding the outer spiracular opening
Phytophagous: feeding on plants
Pinaculum (Pinacula): a small, flat, or slightly elevated chitinized area bearing a seta or setae
Planta: distal part of the proleg bearing the crochets but never bearing setae
Plate: a larger sclerotized area of the body (= Shield)
Posterad: toward the rear
Posterior: caudal or rear
Postspiracular: caudal of the spiracles
Preapical: just before the apex
Prepupa: the nonfeeding portion of the last instar preceding the pupa in which the larva is shorter, thicker, and relatively inactive
Primary setae: those setae with definite locations and numbers found in all instars
Produced: extended or projecting
Prolegs: fleshy, unjointed abdominal legs with or without crochets; false legs
Prothorax: the first thoracic segment
Prothoracic shield: the dorsal shieldlike covering of the first thoracic segment
Proximal: nearest to the point of attachment
R
Recurved: curved backward
Reniform: kidney-shaped
Retinaculum: a projection or toothlike structure on the oral surface of the mandible
Retracted: with the head withdrawn into the prothorax
Retractile: capable of being drawn in
Rudimentary: reduced in size, barely developed
S
Saprophagous: feeding on dead or decaying materials
Scale: a highly modified seta, which is somewhat expanded and usually flattened above
Sclerite: a hardened body plate
Sclerotized: hardened and tanned, so that it is yellow to black in color
Scolus (Scoli): a spinose, usually branched projection of the body wall, each branch bearing a stout seta at its tip
SD: subdorsal setae
Secondary setae: those setae with indefinite locations and numbers, and usually not present in the first instar
Serial: referring to the number of rows of the bases of the crochets
Serrate: sawlike
Seta (Setae): a hairlike projection of the body wall that is articulated in a socket (compare to Spine)
Setal map: a flat, diagrammatic drawing of the arrangement of the setae on one side of a larva
Setose: bearing setae
Shield: a sclerotized plate covering part of the dorsum of a segment
Simple eyes: see Stemmata (or Ocellus)
Sinus: a cavity or depression
Spatulate: spatula-shaped, spoon-shaped; flat, rounded, and broad at the tip, narrowed at the base
Spine: an unarticulated thornlike projection arising from the cuticle (compare to Seta or Spur)
Spinneret: a structure from which silk is spun, usually located on the labium of larvae
Spinulose: bearing little spines
Spiracular line: the line coinciding with or near the spiracles
Spur: a movable spine
Stadium (Stadia): the time period between molts
Stemma (Stemmata): a simple eye of holometabolous larvae
Striate: with grooves and ridges
Subanal: below the anus
Subequal: nearly equal
Submentum: the basal part attaching the labium to the head
Sulcus: a groove or furrow
SV: subventral setae
T
T1: prothorax
T2: mesothorax
T3: metathroax
Tarsus (Tarsi): the fifth segment of the thoracic leg which usually bears a claw (in larvae)
Tentorium: the internal skeleton of the head
Tonofibrillary platelet: a small, external, flattened, sclerotized area of the integument associated with muscle attachment
Transverse band: crochets arranged transversely to the long axis of the body
Triordinal: crochets arranged so the tips are of three alternating lengths
Trisetose: three setae
Truncate: square at the end
Tuft: a group of setae
U
Uniordinal: crochets arranged so they are of a single length or slightly shorter toward the ends of the row
Uniserial: crochets arranged in a single row with their bases in line
Unisetose: one seta
Urticating hairs: hairs or setae connected to poison glands that cause irritation; barbed hairs may also cause irritation without poison
V
V: ventral setae
Venter: the entire upper surface of the body
Verruca (Verrucae): a somewhat elevated area of the cuticle, bearing setae pointing in many directions like a pin-cushion
Vestigial: weakly developed or degenerate; only a remnant left
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