Agapostemon tyleri (Tyler's Agapostemon):   This bright green, striped sweat bee is rare in the Valley.  It is a generalist pollinator.   This species was found visiting candy barrel cactus (Ferocactus wislizeni) at Campos Viejos Ranch in Starr County.

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Andrena miserabilis (miserable mining bee):  This bee appears in early spring at the Mission Hike & Bike in large numbers:  females construct ground nests in hard-packed trails running through the site's extensive groves of prickly pear (Opuntia engelmannii var. lindheimeri) .  I did not find the bees on the cactus, but I've never found this species anywhere else in the Valley except at this one location -- so I'm wondering whether the location is incidental or evidence that the species visits cactus.  It could be that the sandy soil liked by the cactus is also attractive to the mining bees.

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Anthophorula compactula (compact anthophorula):  This is a common spring visitor in the Valley to both prickly pear (Opuntia engelmannii var. lindheimeri) and twisted rib cactus (Thelocactus setispinus).  Although broadly polylectic, this species emerges in the Valley during the spring cactus bloom and is most likely to be found on small, low-growing cacti.  Males sometimes sleep inside Argemone sanguinea. This is a small bee - smaller than a typical honey bee.

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Ashmeadiella cactorum (cactus ashmeadiella):  This generalist species appears on prickly pear (Opuntia engelmannii var. lindheimeri).  Ashmeadiella cactorum is smaller than Ashmeadiella maxima, and less densely haired. The female  Ashmeadiella cactorum also has sparse orange hairs on the outer mandibles.  All male Ashmeadiella have 4 spines/prongs on the tips of their abdomens -- this feature is visible to the naked eye.  On first glance, Ashmeadiella look a little like resin bees, and are sometimes confused with them.

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Ashmeadiella maximum (cactus anthidiellum):  This generalist species appears on prickly pear (Opuntia engelmannii var. lindheimeri).  

 

Augochlora azteca (Aztec sweat bee):   This is a brilliant blue-green bee that visits prickly pear in the Valley (Opuntia engelmannii var. lindheimeri).  I've seen both males and females on prickly pear, but I'm uncertain whether females gather pollen from the cacti or just visit them for nectar.   This species might be confused with the Ceratina cobaltina noted below, but the latter is much smaller and less likely to be found on prickly pear.

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Ceratina cobaltina (cobalt small carpenter bee:  This is an adventive generalist species sometimes found on prickly pear.   It is briliant blue-green and about the size of a large ant.

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Ceratina texana (Texas small carpenter bee:  This generalist pollinator occasionally appears on pitaya (Echinocereus enneacanthus).  It also visits golden prickly poppy (Argemone aenea) .  The Texas small carpenter bee is a dark metallic green.  It is ant-sized and generally smaller than the cobalt small carpenter bee.   

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Coelioxys texanus (Texas cuckoo leafcutter bee):  This cuckoo bees lays eggs in the nests of female Megachile policaris (thumbed leafcutters).  Cuckoo bees do not collect pollen -- they merely drink nectar from plants.  This species has been recorded nectaring on prickly pear.

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Diadasida diminuta (globe mallow bee):  This chimney bee is a mallow speciialist, but it sometimes visits prickly pear.  This is a smallish beige bee that fits easily on the head of a dime.

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Diadasida rinconis (Rincon chimney bee):  This bee is one of the principal cactus-visitors in the Valley.  Many Diadasia, inlcuding this species, are cactus specialists.  This bee is larger than Diadasia diminuta (the globe mallow bee) -- about the size of a small bumble bee.

 

Dianthidium discors (discordant pebble bee):  This species was found visiting candy barrel cactus (Ferocactus wislizeni) at Campos Viejos Ranch in Starr County. Its yellow jagged-striped banding makes it easy to identify.  Females dig into holes in cacti and flash their abdomens at males.  They mate directly on the cacti.

 

Lithurgopsis littoralis (littoral cactus woodborer bee):  This is the dominant Lithurgopsis species of the Lower Rio Grande Valley, and it is the most common cactus polliinator in the Valley.   It looks like a hefty leafcutter with unusually long legs.  Males overnight in prickly poppies. 

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Megachile montivaga (silver-tailed petal-cutter):  This is an uncommon leafcutter bee species.  It is a generalist pollinator that occasionally visits prickly pear.

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Megachile policaris (thumbed leafcutter):  This is also a generalist pollinator that occasionally visits prickly pear.  It is the most likely leafcutter species to encounter on prickly pear in the Valley.  As noted above, it is a host to Coelioxys texanum (the Texas cuckoo leafcutter), which also sometimes visits prickly pear.

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Melissodes opuntiellus  (little prickly pear longhorn bee):   This generalist bee is a common prickly pear visitor in the Valley.  Males sometimes sleep inside Argemone sanguinea.  This species is small for a longhorn bee -- it is about honey bee size.

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Melissodes tepaneca (Tepancec longhorn bee):   This bee is a broad generalist pollinator that occasionally visits prickly pear in the Valley.  It is slightly larger than a honey bee. 

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Osmia subfasciata (faintly-banded mason bee):  This is a blue-green metallic bee, about half the size of a honey bee.  It coes not pollinate cacti, but it does visit prickly pear in the spring for nest-building materials.  The females chew off the new buds of prickly pear pads and carry them to their nest sites.  This bee is easy to identify to subgenus, but species identification may be tricky, because there are at least three small  blue-green metallic mason bees that emerge in spring in the Valley.

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Svastra duplocincta (barrel cactus longhorn):   Svastra duplocincta is a cactus polinator speciaiist.   It appeared in 2022 at Campos Viejos Ranch in Starr County, feeding on candy barrel cactus (Ferocactus wislizeni).   

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Triepeolus vernus (spring triepeolus cuckoo bee):   This is an uncommon cuckoo bee that deposits eggs in the ground nests of longhorn bees -- its exact species host is unknown.  I've found it lurking around the nests of Melissodes opuntiellus and  Anthophorula compactula, and also visiting twisted-rib cactus.  I'd love to find out what its host is.