Long-Palped Ant-Mimic Sac Spider: How to Identify

This mesmerizing species, the Long-palped ant-mimic sac spider, is known to thrive in various habitats, from the ground and beneath logs or rocks to the depths of leaf litter. However, rather than spinning webs like other hunting spiders, the Long-Palped Ant-mimic sac spider stalk their prey on foot. As if that wasn’t enough for them to stand out among their kin, they also mimic carpenter ants by gracefully raising their front legs as antennae!

The long-palped ant-mimic sac spider, known scientifically as Castianeira longipalpa, can be found across the Eastern United States and Pacific Northwest. These tiny black spiders feature at least four white lines trailing along their abdomens — though they are not medically significant in any way.

Long-palped ant-mimic sac spider
A female long-palped ant-mimic sac spider, Castianeira longipalpas, crawling on a piece of rock. Photo credit: Ernie Cooper

Long-Palped Ant-Mimic Sac Spider: Description

The long-palped ant mimic sac spider may not resemble ants, but its behavior is unmistakably similar to that of the red-spotted ant mimic spider (C. descripta). If you observe them closely, they can be seen holding their two front legs up in such a way as to appear like six-legged creatures with antennae – an imitation of the ants! The purpose behind this behavior remains mysterious yet; however, it’s thought that these spiders use this technique to get close enough to capture and prey on unsuspecting ants.

Depending on age and sex, a Long-palped ant-mimic spider can display varying features. The abdomen is always black with at least four lateral white or light gray stripes, while the cephalothorax (head area) ranges from black to brown to almost white. Juveniles have entirely translucent brown legs, whereas adults possess two front leg pairs that transition between dark hues near the body and lighter shades toward their ends.

Adult females of the specimen can grow up to a maximum size of 1/2 an inch (13mm), while males and juveniles are much smaller, ranging from 3-6 mm. Colorations for these specimens may include black with white bands, wholly black, or bicolored in both black and brown.

Long-palped ant-mimic spider does not make a web.

Unlike other Corinnidae species, the long-palped ant mimic sac spider does not create a web to capture prey. Instead, this arachnid actively hunts for ants and other insects. However, it does use its silk-producing capabilities by spinning egg sacs to protect its eggs and build nests where it can house these cocoons.

Long-palped ant-mimic sac spider: Dangerous?

Long-palped ant-mimic sac spider is a speedy spiders, and their speed can be misinterpreted as aggression. In truth, they usually flee when confronted by larger humans or animals. Bites are incredibly uncommon due to their size; however, if one were to occur, the symptoms would likely consist of minor localized distress like swelling or pain comparable to a bee sting.

Further recommended reading about spiders.

Spider pages: Learn how to identify and avoid these spiders.

Peppered jumping spiders.

Spotted ground swift spider.

Spinybacked orb weavers.

Parson spiders.

White spiders.

Striped spider in the U.S.

How long do spiders live?

Spider anatomy 101.

The most venomous spiders in the world.

Zebra spiders.

Furrow orb weaver spider.

Marbled orb weaver spiders.

Red house spider identification.

Purse web spider.

Crab spider: How to identify.

Orb weaver Spiders: How to identify and get rid of them.

Common house spiders: How to Identify and get rid of them.

Dark fishing spiders.

Six-Eyed Sand Spider: Is the White Sand Spider Dangerous?

10 biggest spiders in the world.

The Red widow spider

Giant Huntsman Spider: How to Identify the Largest Spider

Brazilian salmon pink bird-eating tarantula

Brazilian Giant Tawny Red Tarantula

Colombian Giant Redleg Tarantula

Cerbalus Aravaensis: Middle East’s Largest Spider

Camel spiders: Myths and Facts.

Net-casting spiders: How to identify these spiders.

White-tailed spider: How to identify and manage.

Katipo Spider: How to identify New Zealand’s venomous spider

Brown widow spider: How to identify and avoid the false widow.

Redback spiders how to identify them and prevent bites

Funnel weaver spiders vs funnel-web

Cellar spiders how to identify and get rid of them

How to identify the wolf spider

How to identify the hobo spider

Brazilian wandering spider how to identify and avoid

Huntsman spider how to identify the eight legged freak

Jumping spiders how to identify these harmless hunters

Black widow spiders how to identify and avoid

Tarantulas appearance diet and mating

Do tarantulas bite?

Brown recluse spiders how to identify and avoid

Dennis V. Gilmore Jr.

Dennis V. Gilmore Jr. is a former Marine Sergeant and the author of several books, including two on night hunting coyotes and red and gray fox. He has written several hundred articles on predator hunting for ThePredatorHunter.com.

Recent Posts