Identification and Management of Cattail Caterpillar in Grain Sorghum

Introduction

Crop pests and insects are issues that every farmer faces throughout the growing season. While most insects are harmless, there are many insects that can harm your crop without proper prevention or management. Correctly identifying field crop pests and managing them appropriately is essential for maximizing yield potential. A common sorghum pest that can be found throughout the United States and southern Canada is the cattail caterpillar.

Identification

Cattail caterpillars (Acronicta insularis) were first described by Gottlieb August Wilhelm Herrich-Schäffer in 1868.1 The adult moth, which is also called Henry’s marsh moth, is pale brown and may or may not have dark brown markings between the wing veins. The moth’s thorax is white to ivory and covered with soft hairs. The caterpillar or larva is multi-colored with a basic white body that appears more as white stripes because of the broad black dorsal stripe, mottled black-and-white lateral stripe, and bright orange bumps containing bunches of hair which form a band around middle of each abdominal segment.2

The Cattail Caterpillar typically feeds on cattail, smartweed, grasses, poplar, and willow. Its usual habitat includes marsh borders, wooded riverbanks, and generally any damp area where larval host plants grow.

Sorghum fields near water create the perfect habitat for cattail caterpillar populations to thrive. They can cause considerable leaf feeding and damage to the plant. Immature larvae feed on the leaf surface giving the leaf a windowpane appearance. Generally, larger larvae consume leaf tissue from the leaf edges giving the leaf a tattered appearance. They can, but rarely, feed in the whorl and cause large irregular holes in leaves as they unroll from the whorl which could cut the main vein and cause the entire leaf tip to die. 

Management

There is no established treatment threshold as the loss of leaf tissue is usually more cosmetic than yield reducing. Additionally, compared to headworms, cattail caterpillars do not feed on the sorghum head. If a field is surrounded by a marsh or river, the larvae may be found throughout the field compared to field edges. Natural parasitoid predators can help reduce larval populations. Should extreme damage be noted while scouting, a labeled insecticide could be considered. 

Wilson Henry

Technical Agronomist

Sources 

1Acronicta insularis. 2021. Wikipedia. The Free Encylopedia. 

2Balaban, J. and Balaban, J. 2005. Species Acronicta insularis - cattail caterpillar moth - Hodges#9280. BugGuide. https://bugguide.net/node/view/16761

Other Sources:

Varenhorst, A., Rozeboom, P., Anderson, E., and Wagner, P. 2020. An identification guide for sorghum insect pests in South Dakota. South Dakota State University Extension. https://extension.sdstate.edu/.

Lotts, K. and Naberhaus, T. 2021. Henry's Marsh Moth, Simyra insularis (Herrich-Schaffer, 1868). Butterflies and Moths of North America. https://www.butterfliesandmoths.org/

Websites verified 6/30/21.

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