LEIOPODUS CUCKOO BEES 

Genus Leiopodus - Tribe Protepeolini

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The bee tribe Protepeolini occurs only in the Western Hemisphere:  it ranges from the southern United States through South America.  The small genus Leiopodus is the sole member of this tribe.  Like the Nomada, Epeolus and Triepeolus cuckoo bees shown in the preceding sections of this guide, Leiopodus are cuckoo bees of the family Apidae that parasitize the nests of of other bees. 
 

The species Leiopodus singularis

 

Leiopodus singularis is the only member of its genus (and of the tribe Protepeolini) occurring north of Mexico.  Within the United States, this species is found primarily in south Texas, New Mexico, Arizona and southern California.  Its population extends through Mexico and at least as far south as Guatemala.  Leiopodus singularis is considered generally uncommon, and it has been documented rarely in the Valley  -- perhaps because its small size and muted coloring make it inconspicuous in most settings.

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Entomologists Rozen, Eickwort and Eickwort first described the nesting habits of Leiopodus singularis in 1978. 

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Leiopodus cuckoo bees are brood parasites that invade the nests of chimney bees (Diadasia, Melitoma and Ptilothrix).  Leiopodus singularis is a known cleptoparasite of the chimney bees Diadasia angusticeps and D. olivacea.  The female Leiopodus shown here, discovered at the National Butterfly Center in November 2022, was feeding in the vicinity of the chimney bees Diadasia ochracea and Diadasia tropicalis.  (A third chimney bee species, Diadasia diminuta, was also present -- however, Rozen et al. reported in 1978 that this species is not subject to attack by parasitic bees.)

Female Leiopodus singularis are most likely to be found lurking near the nests of their Diadasia hosts. Female Leiopodus singularis may compete with one another at nest sites, facing off in aerial combat.  Diadasia -- which are considerably heftier -- also attack and chase away female Leiopodus singularis from nesting areas.

 

Leiopodus singularis females tend to linger outside of nests, watching and waiting for the hosts to leave. Thereafter, the cuckoos enter the nests and deposit eggs, one by one, in the cell chamber walls.  The cuckoo bees cover the eggs with soil after laying them.  They depart the nests afterward.

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Leiopodus singularis eggs have an unusually long incubation period.  By the time first-instar (first-stage) Leiopodus larva emerge, their hosts' larvae are already preparing to enter the final instar  --  and thus are far larger.  The newly-emerged Leiopodus larvae are barely one mm in length and legless.  Nonetheless, equipped with long, sharp mandibles, they handily kill off the Diadasia larvae. 

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The first-instar Leiopodus larva do not eat; instead, they molt and enter the second instar.  They then consume food provisions stored in the nest by the adult host for her own offspring.