# Orb Weaver Spider — Spider Squad

## Common Name
Orb weaver spider

## Scientific Family
Araneidae (many species — common Ontario species include Argiope aurantia [black and yellow garden spider], Neoscona crucifera, Larinioides cornutus, Araneus diadematus [cross spider])

## Size
Varies significantly by species. Argiope aurantia females: 19 to 28 mm body, among the largest Ontario garden spiders. Smaller species: 5 to 14 mm body.

## Appearance
Highly variable by species. The black and yellow garden spider (Argiope aurantia) is unmistakable — bright yellow and black patterned abdomen, large size, often with a zigzag band of silk (stabilimentum) in the centre of the web. Other orb weavers are brown or grey with varied patterns.

Shared characteristic: the classic circular, spoke-and-spiral web — what most people picture when they think "spider web."

## Behaviour
Orb weavers build and often rebuild their orb-shaped webs daily or every few days. Webs are placed in locations with good insect flight paths: between plants, across open gaps in vegetation, in eaves and window frames, spanning doorways, and on exterior light fixtures (where insects congregate at night).

The spider typically hangs in the centre of the web or retreats to a silk shelter at the web's edge. When prey hits the web, the spider rushes out, bites and wraps it in silk.

## Seasonal Pattern
Ontario orb weavers are most visible and at maximum size in **late August through October** — this is when adult females have reached full size and are laying egg sacs before dying with the first hard frost. The "fall spider invasion" alarm people experience is largely orb weavers becoming large and prominent.

Most Ontario orb weavers complete one generation per year. Eggs overwinter in a silk egg sac. Spiderlings emerge in spring. Adults mature by late summer.

## Where Found
- Garden areas between shrubs and plants
- Exterior eaves and corner overhangs (where the web spans the protected angle)
- Around exterior light fixtures (high insect activity at night)
- Across open gaps in fences, decking, and outdoor structures
- Window frames and door frames on the exterior

They are primarily outdoor spiders. Indoor orb weaver encounters are uncommon.

## Danger Level
Not dangerous. They do not seek human contact. They bite only under direct handling or compression. Bite effects are minimal — localized pain similar to a minor sting.

## Common Concern
The sudden appearance of very large orb weavers in late summer alarms many homeowners who haven't noticed the spider building its web gradually through the season. The spider didn't arrive suddenly — it grew steadily and reached a size where the web becomes very visible.

## Professional Treatment
The perimeter treatment addresses orb weavers on treated building surfaces (eaves, window frames, door frames). Spiders building webs in garden areas away from the treated perimeter are not directly affected, but reducing the insect food supply through perimeter treatment reduces their food source over time.