In Search of Daddy Longlegs

I needed to seal some openings to the space under the house and wanted to be sure no animals had moved in, so we set up an infrared game camera to record nocturnal activity. I had already trapped and relocated 1 raccoon to far out in the hills, but I needed to make sure no one else was living under there. We saw a few mice but, much to our relief, no larger animals went under the house. We learned a few interesting things about what happens around the yard at night along the way.

We have a lot of daddy longlegs around the house and yard in hot weather. We have to work to keep them outside. On hot afternoons they like to congregate under the lean-to attached to the shed or under the eaves near doorways.

Cluster beginning to form

The above photo, taken at about 9:00 AM, shows a small cluster of daddy longlegs on the shed wall. It’s about 8 inches across but I’ve seen basketball-sized colonies. The light-brown spot on the center far right of the cluster is a new member crawling in. He (or she) crawled to the center top of the cluster and settled in. Those black spots on the wall were left by larger clusters in the same location. It’s an eerie sight when a large cluster is pulsating.

Cluster on the way down

The size changes throughout the day. I took this second photo at 5:00 PM, and the cluster is much smaller. Other small clusters were scattered over the shed wall. I went back again a few hours later, just before dark, and all the clusters were gone. The shed wall was still clear at dawn the next morning, but clusters were beginning to form by 8:00 AM

MiniMo triggering infrared camera

Some of the daddy longlegs must spend nights in leaf mold and litter in our woods. MiniMo, one of our semi-feral cats, triggered the game camera just before dawn on her way to the house for breakfast. After MiniMo passed, the camera captured a parade of daddy longlegs. It’s only a 15 second video, but if you watch closely you can see them coming out of the leaves to the left and and climbing the wall on the right. They’re going up to the back porch.

Daddy longlegs leaving leaf mold and climbing porch wall

I could find little information on the daily movements of daddy longlegs but they are described as nocturnal. It is uncertain whether the clusters are defensive or are formed for temperature regulation or some other purpose. I was able to confirm that they like to hang out in leaf mold and are most common in late summer. They are certainly most numerous around here in late summer and early fall. They are sometimes called harvestmen, partly because of the time of year they are most prevalent.

I’d always thought of them as spiders. They and spiders are arachnids, but daddy longlegs are a separate order (Opiliones) of arachnids from spiders (order Araneida). Live and learn, I guess.

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