common name: gladiolus thrips
scientific name: Thrips simplex (Morison) (Insecta: Thysanoptera: Thripidae)

Introduction - Synonymy - Distribution - Description - Host Plants - Management - Selected References

Introduction

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

adult female

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 thrip 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 every where gladiolus are grown in Africa, southern Asia and Japan, Australia, several Pacific Islands, Europe, and North and South America.

In the Unitd 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.

adult - ventral view

head and prothorax

antenna

forewing

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.


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

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.

flower damage

damage to blooms

damage to corms

Management

Florida Insect Management Guide for gladiolus

Selected References

Authors: H.A. Denmark, Florida Department of Agriculture, Division of Plant Industry, and J. F. Price, University of Florida.
Originally published as DPI Entomology Circular 322.
Photographs and Graphics: Division of Plant Industry; Whitney Cranshaw, Colorado State University; Laurence Mound ANIC, CSIRO;
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-36
Publication Date: July 1998. Latest revision: September 2010.
Copyright 1998-2010 University of Florida

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