Like most andrenids, it has small depressions between the eyes and the antennal bases called facial foveae.

Both species are communal, females have provision over one cell each day, and intranest mating is common.

If 2 or more females do share a lateral burrow, each seems to maintain the tunnel at the same level; there is no observed cooperative or agonistic behavior.

The main tunnels are unfinished and extend straight down, while the brood cells are horizontal and have a waterproof lining.

After an egg is laid and the cell is closed, a females then leaves the nest for a feeding trip, not returning with any pollen.

Nests may also be attacked by Solenopsis molesta, a type of fire ant, which takes pupae as prey items.

Females lay eggs and continue to provision and construct brood cells while larvae develop, and some males remain in the nests.

In winter months, larvae remain in diapause, or resting condition, in their prepupal or pharate adult stage.

Macrotera portalis practices bet hedging because only a certain portion of bees emerge in any given year, with many remaining in diapause.

Since M. portalis lives in a desert environment, in which conditions are extremely unpredictable (between year variation is greater than in any other biome), it is likely that this promotes bet hedging in the species.

Larvae are small, exposed to high temperatures, low humidity, buried in the soil, subject to predation, desiccation, and pathogens.

[1] The existence of two different types of males, dimorphism, has been found to be a derived state in this species.

Larval diet and growth influences body size, thus a provisioning female determines which tactic her male offspring will use.

M. portalis has both territorial male behavior in a female emergence site (inside the nests) as well as a resource-based rendezvous site that contains territorial small-headed males, both strategies predicted following the concentration of females in these two specific areas.