So you found a spider

Finding Ummidia

What are they?

Ummidia is a genus of trapdoor spider found in the US from Virginia, south to Florida and west to Arizona. Ummidia are usually around an inch in diameter (including legs) and are black to dark brown, occasionally with a white “heart patch” on top of the abdomen. The abdomen has a dull and slightly fuzzy appearance, and the carapace and legs are frequently quite shiny. Ummidia can be differentiated from all other US trap door spiders by a depression or “saddle” on the tibia of the third leg.

Commonly called “cork door” spiders, Ummidia construct relatively short (3-6”) burrows with a heavy cork type door. The burrows are heavily lined with silk; sometimes so thick that the burrow can actually be pulled from the ground in one piece.

Photo: Chris A. Hamilton

These spiders live underground for most of their lives. Young will stay in their mother’s burrow for some number of months and then emerge to create their own burrows. In some areas they are known to file out of the mother’s burrow and climb a nearby tree to balloon (using silk to float on the breeze, allowing them to disperse farther). Females will remain in their burrow for the rest of their lives (up to ten years or more).The males remain in their new burrow until they reach maturity, at which point they will emerge (frequently all the males of a given species will emerge around the same time of year), and wander until they find a female.

How can I find them?

Ummidia can be found in a few different ways. If you know of an area where Ummidia occur, you can scan the ground for trap doors, though they may be difficult to see. Some people will use a leaf blower and watch for trap doors to pop open. Another method is to go out at night with a headlamp. Ummidia “hunts” at night and will sit with their trap doors slightly open, so they will be slightly

easier to see. You can also use a small shovel or trowel to scrape away the top layer of soil. This will also remove the burrow door and the burrows will become visible. The last method is simply to be out and about during the time of year that the males are moving. You can simply collect them right off the ground!

What do I do when I find one?

Ummidia are generally not aggressive and will frequently play dead if disturbed from their burrows. However, unless you are fairly experienced in handling spiders, the best way to collect a Ummidia you have found is to gently “nudge” the spider into a container (like a small deli cup) using the lid. You can place a small bit of tissue with a drop of water to cushion the spider and keep it from drying out.

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