WSU Whatcom County Extension

Integrated Pest Management for Blueberries

Symphylans

(Scutigerella immaculata)

Insects & Invertebrates

 

Scutigerella

Symptoms

Garden symphylans are an occasional pest, but can cause extensive crop damage when present. They live in the soil and feed on fine roots, which reduces the crop’s ability to take up water and nutrients, leading to general stunting. They are exceptionally injurious to young plants. The symptoms of low vigor and weak growth are usually seen between April and June.

 

Identification

Garden symphylans are not insects but are closely related to centipedes and millipedes. They are white, slender and fragile, about ¼” long with a distinct head. They have between 6 and 12 pairs of legs depending on the age of the symphlans; newly emerged nymphs have 6 pairs of legs and fully mature adults have 12 pairs of legs.

 

Life History

Eggs are deposited starting in the spring and through the summer; they are deposited in groups of 20 and are white and spherical with hexagonal ridges. Length of egg incubation ranges from 12 to 40 days, depending on temperature. Total time from egg to sexually mature adult (seventh instar) is approximately five months at 50°F, decreasing to approximately three months at 70°F and less than two months at 77°F. It is possible to have two complete generations a year at higher soil temperatures. All life stages are found in the soil. Unlike earthworms, they are not able to burrow through the soil and must use existing pores and cracks to move around.

 

Monitoring

Symphylans are generally found in the top 10 to 12 inches of the soil, but can penetrate deeper to find more suitable conditions. They are extremely fast moving and run from light so they are hard to find.

Scout for symphylans before planting.  In late-April through early-June or in September, take 20 shovel-full (1 cubic foot) samples, randomly dispersed through the field.

Symphylans can be baited for monitoring purposes. A potato or carrot can be cut in half and placed cut side down on the ground with a white plastic pot without holes covering the bait. After 2-3 days the cut side of the bait should be checked for symphylans.

 

Thresholds and Management

If an average of 2-5 symphylans found per shovelful, consider a pre-plant treatment, although thresholds are not well established. Remove affected plants in established fields. Soil fumigation can be done in infected fields prior to planting. Spot treatments may be effective.

Tillage can provide some control. To be most effective, tillage should be done when symphylans are in the upper portion of the soil.

 

Resources

Pennsylvania State University, Entomological Notes, Garden Symphylan As A Pest of Field Crops
http://www.ento.psu.edu/extension/factsheets/garden_symphylan.htm

University of California, IPM Online, Cole Crops Garden Symphylans
http://www.ipm.ucdavis.edu/PMG/r108500111.html

WSU Extension Bulletin 1351, Garden Symphylan: Biology and Control
http://cru.cahe.wsu.edu/CEPublications/eb1351/eb1351.pdf

ATTRA, Symphylans: Soil Pest Management Options
http://attra.ncat.org/attra-pub/symphylans.html

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WSU Whatcom County Extension • 1000 N. Forest St., Bellingham, WA 98225 • 360-676-6736 • whatcom@wsu.edu