by Nanette Londeree, Master Rosarian
SIGNS
Eight-legged creatures with two body parts, no wings, no antennae
Silken egg sacs
SYMPTOMS
Shoots and silken webs on leaves
Small burrows in soil that are lined with spider silk
CAUSE
Wide range of spiders of the Class Arachnida and Order Araneae:
Orb weaver and garden spiders (family Araneidae)
Wolf spiders (family Lycosida)
Jumping spiders (family Salticidae)
Crab spiders (family Thomisidae)
OPTIMAL CONDITIONS
Soil with mulch that provides protection and humidity
Places for web attachment
Dense shrubs and coniferous trees
A water source
Flowers and plants that attract prey
TREATMENT
Prevention:
Maintain good garden sanitation – clean up woodpiles, old boards and other debris where spiders often live
Locate where the spiders live and what prey is supporting their population, and eliminate the prey
Use a hose with high-pressure water on the outside of the house to knock down and destroy webs, egg sacs and spiders
Use yellow or sodium vapor light bulbs at outside entrances to reduce night-flying insects (prey) which attract spiders
Elimination:
It’s not recommended to use pesticides for spider control
If necessary, use insecticides that include pyrethrins, resmethrin, allethrin, or combinations of these products
GOOD GUY / BAD GUY?
They are really good guys – they’re voracious predators that eat almost anything
They can rapidly colonize a suitable habitat and eat enormous numbers of insects
Many overwinter as adults and can reduce prey numbers early in the season
Photo of Orb Spider by Alan Goulet, and photo of Wolf Spider by Lawrence Sawyer – both used with permission from:
http://www.istockphoto.com/