Saddle Gall Midge

Key points

• Saddle Gall midge complete one lifecycle a year
• Wheat, barley, rye and, to a lesser extent, oats, can all be affected by Saddle Gall midge
• The presence of galls on the wheat stem can significantly reduce yield
• Saddle Gall midge infestations have increased in recent years, particularly in or near to areas of continuous cropping
• Currently there are no products with recommendations for the control of this pest.

Introduction 

Adult  Saddle Gall midge – Haplodiplosis marginata are approximately 5mm long and easily distinguished by their red/orange colour. Eggs are found on the leaf surface and form a linear pattern following the leaf veins. The larvae are initially white but as they mature develop a red/orange colouration.

The presence of indentations in the stem that are swollen at either end (saddle shaped) are indicative of Saddle Gall midge infestation. These lesions restrict the flow of nutrients to the developing ear which can result in significant reduction in quantity and quality of grain. Where infestations are severe may give rise to buckling of the stem.

Biology
There is only one generation per year of Saddle Gall midge.  Adults appear from May (but have appeared even earlier) and females lay their distinctive orange-red eggs in linear patterns on the leaf surface in early June. There may be several flights of adults. Eggs typically hatch within one to two weeks. Newly hatched larvae migrate down the leaf to the feeding site underneath the leaf sheath. Larvae feed on stem tissue usually in the upper three internodes which gives rise to the characteristic swollen galls. After about a month of feeding, fully grown larvae migrate down the plant to the soil where they overwinter. Heavy clay soils can promote longer dormancy periods of several years. When conditions are favourable in the spring the larvae break diapauses, become mobile and move to the soil surface before pupating and emerging as adults to complete the lifecycle.

Product Choice
There are no approved insecticide treatments with recommendations specifically for control of Saddle Gall midge.