A showy snarl of partridge pea (Chamaecrista fasciculata) lines the sidewalk to my front door. This native member of the pea family (Fabaceae) is an annual, and easily grown. My yard – front and back – is full of native flora, as natives greatly spike the fauna, especially insects. Partridge pea is an especially interesting case of coevolutionary relationships between plants and insects. All of these images were shot in the patch of pea shown in this photo, in about a half hour.
A bumble bee in the genus Bombus approaches a partridge pea flower. Bumbles are certainly the most noticeable and probably most numerous insect pollinator, at least in my flower patch. It’s interesting to listen to them “buzz pollinate” the flowers by rapidly and noisily vibrating their wings to cause pollen to fall from the stamens.
There is another less obvious and arguably more interesting way in which partridge pea lures insects into its foliage. This is an extrafloral nectary, located near the base of leaf petioles. Extrafloral nectaries are like tiny cups that constantly exude a rich sugary secretion. This substance, which is about 95% sugar, is irresistible to certain insects, especially those in the Hymenoptera (ants, bees, wasps).
An ant (species unknown to me) drinks from an extrafloral cup. Ants may be the best known visitors of partridge pea extrafloral nectaries, and I learned about this relationship about a decade ago. But many other insects visit the sugar cups, on partridge pea and the other 2,000 or so plants in over five dozen families worldwide. One theory is that by enticing predatory insects, as many ants and wasps are, into the foliage via extrafloral nectaries, they will discourage herbivory and flower damage by attacking insect herbivores such as caterpillars.
A beetle bandit (Cerceris ssp.) sips from a nectary. Various beetles such as weevils can be major floral consumers, so perhaps beetle bandit wasps – well known to prey on weevils – pay the plant back by controlling these insects.
This Mexican grass-carrying wasp, Isodontia mexicana, is looking a bit tattered. Isodontid wasps are one of the more frequent visitors to my partridge peas. They prey on tree crickets and other small Orthopterans, and this group feeds on foliage.
A spider wasp in the genus Auplopus stuffs its face. Many spider wasp species are high strung and edgy, habitually twitching their wings and moving about rapidly as they hunt prey.
A personal favorite and a spectacular wasp, the yellow-legged mud dauber (Sceliphron caementarium). The insect is the very definition of “wasp-waisted”. They make mud nests which are attached to walls, rocks or other structures. These adobe crypts are provisioned with paralyzed spiders for the wasp larvae to nosh on.
I have seen many other insect species visiting the extrafloral nectaries, and hope to spend some more time photo-documenting them. Oh, one might wonder why someone like me would wish to entice wasps and bees into close proximity to my front door and walkway. It’s not a problem. These insects are non-aggressive, quite busy with their activities, and pay us no mind. In many years of sticking my camera in the faces of stinging insects, I have only been stung a few times – and those were by bald-faced hornets after apparently approaching their large paper nests a bit too close.