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Publication #EENY-036

 

Gladiolus Thrips,Thrips simplex(Morison) (Insecta: Thysanoptera: Thripidae)1

H. A. Denmark and J. F. Price2

Introduction

The gladiolus thrips causes deformities and discoloration of gladiolus flowers, and corms (bulbs) become soft and are prone to decay.

Figure 1. 

Adult female gladiolus thrips, Thrips simplex (Morison).


Credit: Division of Plant Industry
[Click thumbnail to enlarge.]

Synonymy

The gladiolus thrips was described by Morison (1930) as Physothrips simplex from five female specimens collected on carnation flowers, Dianthus caryophyllus, from Urrbrae, South Australia. The holotype and one paratype are deposited in the British Museum.

Moulton and Steinweden (1931) described this thrips under the name Taeniothrips gladioli from Ontario, Canada, and it was synonymized by Steele (1935). Bhatti (1969) placed gladioli in the genus Thrips. Kellie O'Neill of the U.S. National Museum (retired) has suggested that this thrips probably originated in Africa as did its preferred host, gladiolus, Gladiolu x hortulanus.

Distribution

Gladiolus thrips is widespread and is found almost everywhere gladiolus are grown in Africa, southern Asia and Japan, Australia, several Pacific Islands, Europe, and North and South America.

In the United States, it is found in almost all states. It was first found in Florida in 1932 (Watson 1941).

Although it cannot overwinter out-of-doors in northern Europe and northern North America, the annual spread of this thrips probably results from its infested corms being shipped to all parts of the country.

Description

Adults emerge milky-white, but soon turn brown and begin feeding. The female is approximately 1.65 mm long and slightly larger than the male. The antennae are dark brown except for the 3rd segment which is light brown. The wings have a light tranverse band near the base. The first vein of the forewing has seven setae on the distal half.

Figure 2. 

Ventral view of an adult female gladiolus thrips, Thrips simplex (Morison). Photograph by: Laurence Mound ANIC, CSIRO; Illustration courtesy of http://www.padil.gov.au/ Used with permission.


[Click thumbnail to enlarge.]

Figure 3. 

Head and prothorax of the gladiolus thrips, Thrips simplex (Morison), showing setae. Credits: Division of Plant Industry


[Click thumbnail to enlarge.]

Figure 4. 

Antenna of the gladiolus thrips, Thrips simplex (Morison), showing the light brown segment. Photograph by: Laurence Mound ANIC, CSIRO; Illustration courtesy of http://www.padil.gov.au/ Used with permission.


[Click thumbnail to enlarge.]

Figure 5. 

Forewing of an adult gladiolus thrips, Thrips simplex (Morison). Note the first vein with about seven setae on the distal half. Photograph by: Laurence Mound ANIC, CSIRO; Illustration courtesy of http://www.padil.gov.au/ Used with permission.


[Click thumbnail to enlarge.]

The egg is about 0.3 mm long, opaque white, smooth, and bean-shaped. Eggs are deposited in the leave tissue and corms. The two larval stages are light yellow and are usually found beneath the leaves or bracts. The fully developed second instar larva is about the size of the adult. The first pupal stage is distinguished from the second pupal stage by having forward projecting antennae and short wing pads.The 2nd pupal stage, which is a quiescent period, has the antennae folded over the back and much longer wing pads.

Figure 6. 

From left to right: egg and first larval stage, second larval stage, first pupal stage, second pupal stage.


Credit: Division of Plant Industry
[Click thumbnail to enlarge.]

Host Plants

The thrips feed and reproduce primarily on gladiolus flower spikes and corms; however, it has been recorded from Philodendron selloum, Clitoria sp., Rhododendron indicum, Calendula, and crow-foot grass, Eleusine indica. This thrips has never been reared from these plants and they cannot be considered valid hosts. It was reported to reproduce on Tritonia sp., Tigridia sp., and Kniphofia sp.

Figure 7. 

Flower damage caused by feeding of the gladiolus thrips, Thrips simplex (Morison).


Credit: Whitney Cranshaw, Colorado State University, www.ipmimages.org
[Click thumbnail to enlarge.]

Figure 8. 

Gladiolus bloom damage (on right), produced by gladiolus thrips, Thrips simplex (Morison), feeding.


Credit: Division of Plant Industry
[Click thumbnail to enlarge.]

Figure 9. 

Gladiolus corm on right showing advanced stage of injury by gladiolus thrips, Thrips simplex (Morison).


Credit: Division of Plant Industry
[Click thumbnail to enlarge.]

Management

Florida Insect Management Guide for gladiolus, http://edis.ifas.ufl.edu/ig005

Selected References

Bhatti JS. 1969. Taxonomic studies in some Thripini (ThysanopteraThripidae). Oriental Insects 3: 373-382.

Magie RO, Overman AJ, Gilbreath JP, Waters WE, Wilfret GJ, Price JF, Woltz SS. 1988. Gladiolus corm production. Gladio Grams Bulletin No. 69 2-28.

Mizell RF, Fasulo TR, Short DE. (2002). WoodyBug: pest and beneficial arthropods of southeastern U.S. woody ornamentals [17 August 2012]. University of Florida/IFAS. CD-ROM. SW 119.

Morison GD. 1930. On a collection of Thysanoptera from South Australia. Bulletin of Entomological Research. 21 9-14.

Moulton, Dudley, Steinweden JB. 1931. A new Taeniothrips on gladiolus. Canadian Entomologist 43 20-21.

Steele, Vevers H. 1935. Thrips investigation Some common Thysanoptera in Australia. Council for Scientific and Industrial Research, Commonwealth of Australia, Pamphlet 54. 59 pp.

Watson JW. 1941. The gladiolus thrips in Florida. University of Florida Agricultural Experiment Station Bulletin 357. 23 pp.

Footnotes

1.

This document is EENY-036 (IN163) (originally published as DPI Entomology Circular 322), one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: June 1998. Revised: January 2007 and September 2010. This document is also available on Featured Creatures Website at http://entomology.ifas.ufl.edu/creatures. Please visit the EDIS Website at http://edis.ifas.ufl.edu.

2.

H. A. Denmark, Florida Department of Agriculture, Division of Plant Industry, and J. F. Price, Entomology and Nematology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.