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Mission, Texas

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Tribe Anthidiini - Genus Anthidium

Known by the common name “pebble bees,” Dianthidium mix plant resin with materials such as soil, mud, pebbles and plant parts to construct nests.  Bees of the genus Dianthidium are solitary, but sometimes their nests are conjoined or constructed nearby one another.


Dianthidium are often black with ivory or yellow markings, and their bodies and heads tend to be pitted and relatively hairless.  Like leafcutters, mason bees, resin bees and other members of the family Megachilidae, Dianthidium carry pollen on scopal hairs under their abdomens.  The forewings of pebble bees  have two submarginal cells, and their feet have arolia.

Distinguishing traits of the genus Anthidieullum

Traits that aid in distinguishing bees of the genus Dianthidium, shown here, include the following.  (1) The bee's pronotal lobes (on either side of the front of the thorax) are expanded and have thin and translucent edges.  (2) The rear margin of a Dianthidium scutellum (the second thorax segment) is semicircular and convex.  (3) The male Dianthidium has a prominent spine on each hind coxa (upper leg), visible when the bee is viewed from the side.

Dianthidium species are differentiated by such traits as the pale or yellow patterns on their faces, bodies and legs; their size; color; and other minute characteristics. 


The female Dianthidium discors shown here were found visiting candy barrel cactus in mid-June, at the Campos Viejos Ranch, located one hour north of Rio Grande City in Starr County.  This website's authors observed numerous male and female bees engaging in a mating ritual consisting of the following behavior.  Female Dianthidium discors would land on candy barrel cacti and, without stopping to collect pollen or drink nectar, would search for shallow holes in the stalks of the cactus blossoms or buds. The female Dianthidium then buried their heads in the holes while pointing their exposed abdomens upward, displaying their bold yellow-and-black-patterns.  This behavior attracted male bees, which would descend and mate with the females directly on the cactus flowers.


Order:   Hymenoptera

Family:   Megachilidae

Subfamily:   Megachilinae

Tribe:  Anthidiini

Genus:  Dianthidium

Species shown on this page:  
    Dianthidium (Dianthidium) discors

Dianthidium discors; Dianthidium; pebble bee; Copyright 2022 Sharp-Eatman Nature Photography

A male Dianthidium discors

 Dianthidium discors

Coxal spine on the leg of a male Dianthidium discors

Dianthidium discors

The translucent pronotal lobes of a female Dianthidium discors.  Note also the semi-circular rear margin of the scutellum.

Associated plants: 

Candy barrel cactus

(Ferocactus wislizeni)
Family: Cactaceae

(Guaiacum angustifolium)
Family:  Zygophylaceae

​When and where seen:  

May 6, June 21, 2021

La Puerta Tract NWF
(Starr County)

Campos Viejos Ranch

(Near Rio Grande City,

Starr County)

Discordant pebble bee

Dianthidium (Dianthidium) discors

Family:  Megachilidae

Size:   8 mm  (female)

           9-10 mm (male)

Dianthidium discors; Dianthidium; pebble bee; Copyright 2022 Sharp-Eatman Nature Photography

A female Dianthidium discors

A male Dianthidium discors

A male Dianthidium discors

The yellow patterns on the abdomens of male and female Dianthidium discors differ enough to make the bees appear, at first glance, to belong to separate species.  Both patterns, however, are distinctive and aid in identifying Dianthidium discors.  Other features that distinguish this species include the following.  (1) The female’s clypeus is entirely dark.  (2)  Males have yellow markings covering most of the clypeus, labrum and mandibles. (3) The female and male bees’ thoraxes are largely black, with yellow spots on the front edges of the scutum and scutellum, and a narrow, yellow, medial strip lining the scutellum’s back edge.

Dianthidium Species of the Lower Rio Grand Valley

CITE THIS PAGE:  Sharp, Paula and Ross Eatman.  "Dianthidium."  Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019,  Accessed [day/month/year guide accessed].

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