Tomato Hornworms Become Five Spotted Hawkmoths (Manduca quinquemaculata)

Summary: Tomato hornworms become five spotted hawkmoths (Manduca quinquemaculata) via the metamorphic pupal stage in the New World native insect's life cycle.

five spotted hawkmoth Manduca quinquemaculata, Cuivre River State Park, Lincoln Hills region, northeastern Missouri: Andy Reago & Chrissy McClarren, CC BY 2.0, via Wikimedia Commons

Tomato hornworms become five spotted hawkmoths (Manduca quinquemaculata) by undergoing dramatic metamorphosis as pupae, the third stage in the New World native insect’s four-stage life cycle.

The first stage, as eggs, may last from two to eight days. The average duration of the egg stage is five days.

The spherically or ovally shaped egg has a tiny diameter of about 1.50 millimeters (0.059 inches). Egg color varies from light green to white. Egg deposition occurs mainly on leafy undersides but may also happen on the uppersides of foliage. Each egg is deposited singly.

The second stage, as larvae, lasts an average of about 20 days. Larvae are known popularly as caterpillars.

Usually the larval stage consists of five instars (Latin: instar, “form, likeness”). Occasionally larvae undergo a sixth instar. Instars are stages between molts, in which larvae shed their waxy skin, or cuticle, in a process known as ecdysis (Ancient Greek: ἐκδύω, ekduo, "to take off, strip off”). The five instars measure successive mean larval body lengths of 6.7 millimeters (0.26 inches), 11.2 millimeters (0.44 inches), 23.4 millimeters (0.92 inches), 49.0 millimeters (1.92 inches) and 81.3 millimeters (3.2 inches).

The tomato hornworm larva has a cylindrical shape that is punctuated by five pairs of prolegs. The small, fleshy stubs extend from the ventral surface, or underside, of the abdomen, which is the third and final segment of the caterpillar’s body.

Three pairs of jointed legs extending from the thorax are known as thoracic legs. As the second segment in the caterpillar’s body, the thorax continues from the head and leads into the abdomen.

A noticeable feature is the protrusion of a thickly pointed, hornlike structure on the dorsal, or upper, side of the last abdominal segment. The tomato hornworm’s horn usually is black or bluish black in color.

The tomato hornworm distinctively displays eight white or yellow v-shaped lines on both sides of its green body.

With maturity, caterpillars drop from host plants. They make soil burrows, at shallow depths of 10 to 15 centimeters (3.93 to 5.9 inches), to pupate.

The third stage, as pupae, is of variable duration. Pupae measure lengths of 45 to 60 millimeters (1.77 to 2.36 inches).

The elongated oval shape of the large, brown or reddish brown pupae forms a point at the posterior end. A distinctive feature of the pupal stage is a long structure, known as a maxillary loop, that covers the mouthparts. The maxillary loop extends from the mouthparts backward to about one-third of the pupal length.

The adult stage emerges as a large moth with a big head and a stout abdomen. The species name of quinquemaculata recognizes the five orange-yellow spots that mark each side of the abdomen.

Wing span measures 9 to 13.5 centimeters (3 9/16 to 5 5/16 inches). The forewings are a blur of gray or gray brown. A white band extending from the base of the hindwing is zigzagged across the middle with two dark bands before turning into a dark posterior band.

Tomato hornworms become five spotted hawkmoths in a four-stage cycle that ends with the moths' deaths but restarts with each egg, laid singly, that the female moths have deposited on host plants.

view of back (upperside) of tomato hornworm caterpillar, late instar larva; note black "horn" at posterior end (near plant stem): Whitney Crenshaw/Colorado State University/Bugwood.org, CC BY 3.0, via Forestry Images

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

five spotted hawkmoth Manduca quinquemaculata, Cuivre River State Park, Lincoln Hills region, northeastern Missouri: Andy Reago & Chrissy McClarren, CC BY 2.0, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:-_7776_%E2%80%93_Manduca_quinquemaculatus_%E2%80%93_Five-spotted_Hawk_Moth_(14935916497).jpg?uselang=fr

tomato hornworm caterpillar: Whitney Crenshaw/Colorado State University/Bugwood.org, CC BY 3.0, via Forestry Images @ http://www.forestryimages.org/browse/detail.cfm?imgnum=5304021

For further information:

Day, Eric. “Hornworms on Tomato.”
Available @ http://pubs.ext.vt.edu/3104/3104-1551/3104-1551.html

“Five-spotted hawkmoth Manduca quinquemaculata (Haworth, 1803).” Butterflies and Moths of North America > Species.
Available @ http://www.butterfliesandmoths.org/species/Manduca-quinquemaculata

“How to Tell the Difference Between Tomato and Tobacco Hornworms.” Entomology Today > 2013. Dec. 14, 2013.
Available @ https://entomologytoday.org/2013/12/14/how-to-tell-the-difference-between-tomato-and-tobacco-hornworms/

“Manduca quinquemaculata (Haworth, 1803) Five-spotted Hawk Moth.” Pacific Northwest Moths > Family Sphingidae > Subfamily Sphingidae > Manduca.
Available @ http://pnwmoths.biol.wwu.edu/browse/family-sphingidae/subfamily-sphinginae/manduca/manduca-quinquemaculata/

"Manduca quinquemaculata (tomato hornworm)." CABI (Centre for Agriculture and Biosciences International) > Invasive Species Compendium > Datasheets.
Available @ http://www.cabi.org/isc/datasheet/44564

Marriner, Derdriu. “Tomatoes Love Marigolds: Tomato Companion Planting.” Earth and Space News. Thursday, Feb. 19, 2015.
Available @ https://earth-and-space-news.blogspot.com/2015/02/tomatoes-love-marigolds-tomato.html

Moeller, Karla. “Manduca Growth Experiment.” Arizona State University Ask A Biologist.
Available @ https://askabiologist.asu.edu/manduca/introduction

“Moth Anatomy.” Wildlife Insight > Guide to British Moths.
Available @ http://www.wildlifeinsight.com/guide-to-british-moths/moth-anatomy/

NC Small Fruit and Tobacco IPM. “How to ID Two Common Hornworms.” YouTube. Dec. 11, 2013.
Available @ https://www.youtube.com/watch?v=4IRcFWakMlY

Palache, Spencer. “Farmers Menace to Colorful Hoverer: The Five Spotted Hawk Moth.” Havasi Wilderness Foundation. March 16, 2015.
Available @ http://www.havasiwf.org/farmers-menace-to-colorful-hoverer-the-five-spotted-hawk-moth/

Villanueva, J. Raul. “Common name: tobacco hornworm scientific name: Manduca sexta (Linnaeus) (Insecta: Lepidoptera: Sphingidae), common name: tomato hornworm scientific name: Manduca quinquemaculata (Haworth) (Insecta: Lepidoptera: Sphingidae).” University of Florida Entomology and Nematology Department > Featured Creatures. June 1998. Latest revision November 2013.
Available @ http://entnemdept.ufl.edu/creatures/field/hornworm.htm