Blue-Black Spider Wasps

Anoplius spp.

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Blue-black spider wasp resting on senna foliage
This is one of nearly 50 North American species of blue-black spider wasps (genus Anoplius). Note the long legs, and the stout spines at the outer tip of the tibia segment of the hind legs.
Johnny N. Dell, Bugwood.org
Other Common Name
Anoplius Spider Wasps
Family

Pompilidae (spider wasps) in order Hymenoptera (ants, bees, wasps)

Description

There are nearly 50 North American species of blue-black spider wasps (genus Anoplius). Like other spider wasps, they have long legs, with stout spines at the outer tip of the tibia segment of the hind legs. Many species in this genus are entirely black, with a bluish sheen, while many others have an orange marking on the abdomen.

Females hunt wolf spiders, grass spiders, and similar spiders on the ground, flicking their wings nervously. Like other spider wasps, they drag their spider prey into an underground burrow, then lay an egg on it. The wasp larva hatches and eats the paralyzed but still-living spider.

These wasps are often seen visiting flowers.

Learn more about this and other spider wasps on their group page.

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Black and rust-colored wasp resting on blackberry fruit
Blue-Black Spider Wasp on Blackberry Fruit
This blue-black spider wasp might be Anoplius americanus, which has different regional color forms across North America. Females hunt wolf spiders on the ground, flicking their wings nervously. These wasps are often seen visiting flowers.
Ecosystem connections

The blue-black spider wasps that have an orange patch on their abdomen apparently are the species that Mydas flies mimic. In this case of Batesian mimicry, the harmless fly looks intimidating to would-be predators because it looks almost identical to the spider wasps, which are capable of delivering a painful sting.