Classification

Noctuoidea: Noctuidae: Plusiinae: Trichoplusia ni (Hübner)

Common name

cabbage looperlooper:
a caterpillar with some prolegs reduced or missing, usually on segments A3-5 (Geometridae) or A3-4 (Noctuidae)
, cabbage worm

Synonyms

Plusia innata, Autographa brassicae

Larval diagnosis (Detailed)

The larvalarva:
the stages between the egg and pupa of those insects having complete metamorphosis
of the cabbage looperlooper:
a caterpillar with some prolegs reduced or missing, usually on segments A3-5 (Geometridae) or A3-4 (Noctuidae)
, Trichoplusia ni, has been described many times. Some examples are Crumb (1956)Crumb (1956):
Crumb, S. E. 1956. The Larvae of the Phalaenidae. U. S. Department of Agriculture Technical Bulletin 1135. 356 pp., Okumura (1961)Okumura (1961):
Okumura, G. T. 1961. Identification of lepidopterous larvae attacking cotton. California Department of Agriculture Bureau of Entomology Special Publication 282. 80 pp., Peterson (1962)Peterson (1962):
Peterson, A. 1962. Larvae of insects: an introduction to Nearctic species. Part I: Lepidoptera and plant infesting Hymenoptera. Columbus, Ohio. 315 pp., Eichlin and Cunningham (1978)Eichlin and Cunningham (1978):
Eichlin, T. D. and H. B. Cunningham. 1978. The Plusiinae (Lepidoptera: Noctuidae) of America North of Mexico, emphasizing genitalic and larval morphology. USDA Agricultural Research Service Technical Bulletin 1567. 222 pages., Godfrey (1987)Godfrey (1987):
Godfrey, G. L. 1987. Noctuidae (Noctuoidea), pp. 549-578. In F. W Stehr (ed.). Immature Insects. Kendall Hunt Publishing Company. Dubuque, Iowa., LaFontaine and Poole (1991), Sannino et al. (1993), Beck (1999-2000), Ahola and Silvonen (2005)Ahola and Silvonen (2005):
Ahola, M. and K. Silvonen. 2005. Larvae of Northern European Noctuidae. Volume 1. KuvaSeppala Group Limited. Vaasa, Finland. 657 pp., and Wagner et al. (2011)Wagner et al. (2011):
Wagner, D. L., D. F. Schweitzer, J. B. Sullivan and R. C. Reardon. 2011. Owlet caterpillars of eastern North America. Princeton University Press, New Jersey. 576 pp.. LaFontaine and Poole (1991), Beck (1999-2000), Ahola and Silvonen (2005)Ahola and Silvonen (2005):
Ahola, M. and K. Silvonen. 2005. Larvae of Northern European Noctuidae. Volume 1. KuvaSeppala Group Limited. Vaasa, Finland. 657 pp., and Wagner et al. (2011)Wagner et al. (2011):
Wagner, D. L., D. F. Schweitzer, J. B. Sullivan and R. C. Reardon. 2011. Owlet caterpillars of eastern North America. Princeton University Press, New Jersey. 576 pp. published colored illustrations of the larvalarva:
the stages between the egg and pupa of those insects having complete metamorphosis
.

Typically, T. ni can be recognized by having vestigialvestigial:
weakly developed or degenerate; only a remnant left
prolegs on A3 and A4, the second and third ridges (ribs) of the mandible extending to the scissorial (cutting) teeth, a smooth cuticle with minute granules (not microspinesmicrospines:
minute spines on the body, usually visible only under magnification
) under high magnification, and the equally spaced mesothoracic pinaculapinaculum:
a small, flat, or slightly elevated chitinized area bearing a seta or setae
(LaFontaine and Poole 1991). The cuticular texture of T. ni was illustrated in Ichinose (1962: plateplate:
a larger sclerotized area of the body; = shield
14: 8). For doubtful cases, the raduloid of the hypopharyngeal complexhypopharyngeal complex:
a structure consisting of the Hypopharynx, Labial palpi, and Spinneret
has ten ridges (Eichlin and Cunningham 1978Eichlin and Cunningham 1978:
Eichlin, T. D. and H. B. Cunningham. 1978. The Plusiinae (Lepidoptera: Noctuidae) of America North of Mexico, emphasizing genitalic and larval morphology. USDA Agricultural Research Service Technical Bulletin 1567. 222 pages.) but this character usually cannot be scored at less than 400x even when slide mounted. The head never has contrasting dark setal bases or a genal line, but early instars do have black thoracic legs and black subdorsal abdominal spots (SPIC), a color pattern similar to Pseudoplusia includens. However, the mouthparts of the two species are completely different. Gardner (1947)Gardner (1947):
Gardner, J. C. M. 1947. On larvae of the Noctuidae (Lepidoptera) - III. Transactions of the Royal Entomological Society of London 98: 59-89. and Ichinose (1962)Ichinose (1962):
Ichinose, T. 1962. Studies on the noctuid subfamily Plusiinae of Japan. Bulletin of the Faculty of Agriculture, Tokyo University of Agriclture and Technology 6: 1-127. used the maxillary palpimaxillary palp:
a small, segmented sensory structure arising from the maxilla
to seperate T. ni from related species in India and Japan.

Ahola and Silvonen (2005: 265) described T. ni as having the distance between D1 and D2 equal to that between D2 and SD2 on the mesothoraxmesothorax:
the second thoracic segment
, but disagreed with other authors by considering the cuticle as smooth to slightly spiny. Beck (1999: 260) also mentioned the thoracic setal spacing, but he described it as D1, D2 and SD2 being equally spaced on the mesothoraxmesothorax:
the second thoracic segment
and metathoraxmetathorax:
the third thoracic segment
.

The vestigialvestigial:
weakly developed or degenerate; only a remnant left
prolegs can be difficult to see in some specimens. It helps to use light from below the specimen and to roll the larvalarva:
the stages between the egg and pupa of those insects having complete metamorphosis
to create different views. SD1 on A9 is hairlike in the Argyrogrammatini, including T. ni, so the condition of SD1 can be a helpful clue when trying to find the vestigialvestigial:
weakly developed or degenerate; only a remnant left
prolegs. They are not present unless SD1 is hairlike on A9.

Identification Authority (Detailed)

Trichoplusia ni is highly polyphagous and widely distributed. It occurs from Canada to Argentina in the New World but is more sporadic in the Old World (LaFontaine and Poole 1991). The Commonwealth Institute of Entomology map (1974) does not list it from northern Europe, Russia and parts of Africa or Asia. It is absent from Australia (Edwards 1996Edwards 1996:
Edwards, E. D. 1996. Noctuidae, pp 291-333. In E. S. Nielsen, E. D. Edwards and T. V. Rangsi (eds.). Checklist of the Lepidoptera of Australia. Monographs on Australian Lepidoptera 4. Commonwealth Scientific and Industrial Research Organisation. Melbourne, Australia. 529 pp.) and rare under natural conditions in the Netherlands (Bretherton et al. 1983Bretherton et al. 1983:
Bretherton, R. F., B. Goater and R. I. Lorimer. 1983. Noctuidae (part II) and Agaristidae. In: J. Heath and A. M. Emmet (eds.). The Butterflies and Moths of Great Britain and Ireland. Harley Books. Colchester, England. 459 pp.). Otherwise it can be expected from the rest of the world where winter temperatures are mild.

Trichoplusia ni identification is an excellent example of the clash between the theoretical and the practical worlds of quarantine entomology. Of course, species identification of all the interceptions is the goal. But for the New World, given the volume of the interceptions and the lack of time to do dissections, it is rarely worth the effort to try and identify T. ni from Mexico, Central America, and usually South America. The host list of T. ni reads "like a compendium of herbaceous plants of the world" (LaFontaine and Poole 1991) suggesting that cataloging all the plants infested with this species is of little value when we can assume it could occur on almost any herbaceous host. With limited resources, from a United States perspective, it is best to just stop at subfamily if the larvalarva:
the stages between the egg and pupa of those insects having complete metamorphosis
is in the tribe Argyrogrammatini (T. ni and relatives) from the New World. If a species name is needed for a special risk assessment, the mouthparts can be mounted and larvaelarva:
the stages between the egg and pupa of those insects having complete metamorphosis
identified with existing keys.

On the other hand, Weisman (1986)Weisman (1986):
Weisman, D. M. 1986. Keys for the identification of some frequently intercepted lepidopterous larvae. U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine series 81-47. 64 pp. did not list T. ni from the Old World. Perhaps he wanted to imply that Old World interceptions should not go to species. Identification of T. ni from Europe, North Africa, and the Middle East is possible with Beck (1999-2000) or Ahola and Silvonen (2005)Ahola and Silvonen (2005):
Ahola, M. and K. Silvonen. 2005. Larvae of Northern European Noctuidae. Volume 1. KuvaSeppala Group Limited. Vaasa, Finland. 657 pp.. Beardsley (1982)Beardsley (1982):
Beardsley, J. W. Jr. 1982. A key to the late instar larvae of some Hawaiian Noctuidae. Proceedings of the Hawaiian Entomological Society 24: 37-49. can be used for interceptions from Hawaii. However, Kitching (1987: 144) noted that Trichoplusia contains about 50 potentially unrelated species that form one of the most difficult problems to resolve in the systematics of the Plusiinae. Given this uncertainty, it seems safest to identify Trichoplusia-like interceptions from most of Africa or Asia only to subfamily.

Origin records

Trichoplusia ni has been intercepted from the following locations:

Antigua and Barbuda, Brazil, Canada, Chile, China, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Germany (?), Guatemala, Guyana, Hawaii, Israel, Italy, Jamaica, Kenya, Mexico, Netherlands, Nicaragua, Palestinian Territory, Peru, Yemen

Host records

Trichoplusia ni has been intercepted on the following hosts:

Aconitum sp., Allium sativum, Allium sp., Aloe vera, Alstroemeria sp., Amaranthus caudatus, Amaranthus sp., Anemopsis californica, Anethum graveolens, Anethum sp., Anthriscus cerefolium, Anthurium sp., Antirrhinum majus, Antirrhinum sp., Apium graveolens, Apium sp., Arachis hypogaea, Artemisia abrotanum, Artemisia dracunculus, Aster sp., Basilicum sp., Bellis perennis, Bellis sp., Brassia sp., Brassica oleracea, Brassica oleracea var. acephala, Brassica oleracea var. alboglabra, Brassica oleracea var. botrytis, Brassica oleracea var. capitata, Brassica oleracea var. italica, Brassica pekinensis, Brassica rapa, Brassica rapa ssp. pekinensis, Brassica sp., Bupleurum sp., Callistephus sp., Campanula sp., Capsicum annuum, Capsicum sp., Carthamus sp., Carthamus tinctorius, Celosia sp., Cestrum sp., Chenopodium berlandieri ssp nuttalliae, Chrysanthemum sp., Citrus sp., Coriandrum sativum, Coriandrum sp., Crotalaria longirostrata, Cucurbita maxima, Cucurbitaceae, Cymbidium sp., Dahlia sp., Daucus carota, Daucus sp., Delphinium elatum, Delphinium sp., Eruca sativa, Fragaria sp., Gerbera sp., Gloriosa sp., Helianthus annuus, Helianthus sp., Hydrangea sp., Hypericum sp., Juniperus sp., Lactuca sativa, Lactuca sp., Lamiaceae, Lantana sp., Leonotis sp., Liatris sp., Limonium sp., Luffa sp., Mathiola sp., Matthiola incana, Matthiola sp., Mentha arvensis, Mentha morocco, Mentha officinalis, Mentha piperita, Mentha sachalinensis, Mentha sp., Moluccella laevis, Moluccella sp., Musa sp., Ocimum basilicum, Ocimum sp., Ocimum tenuiflorum, Oncidium basilicum, Opuntia sp., Origanum majorana, Origanum sp., Origanum vulgare, Persea americana, Persea sp., Petroselinum crispum, Phaseolus sp., Phaseolus vulgaris, Piper sp., Pisum sativum, Polianthes sp., Porophyllum sp., Portulaca oleracea, Prunus domestica, Raphanus raphanistrum, Rosa sp., Rosmarinus officinalis, Rosmarinus sp., Saccharum sp., Salvia officinalis, Salvia sp., Sandersonia sp., Sechium edule, Solidago canadensis, Solidago sp., Spinacia sp., Statice sp., Tagetes sp., Thymus sp., Thymus vulgaris, Trachelium sp., Zea mays