Crawlies with Cri: Pollen wasp

(Photo by Christy Solo for Illinois Valley News)

Pollen wasp (Genus Pseudomasaris)

This week marks the 10-year anniversary of Crawlies! Let’s celebrate with an ab fab standout wasp!
Don’t panic! This week’s crawly is the vegan of the wasp world. Meet the pollen wasp (Genus Pseudomasaris). Because pollen wasps are solitary, shy, chill and rarely sting, they’ve evolved to look like their more defensive yellowjacket cousins. Clever girls! A quick way to identify a pollen wasp is by the club-tipped antennae; their other vespid wasp cousins have straight antennae.
Pollen wasps are unique in many ways. First, in the United States they are a strictly western wasp; they can be found from Washington to as far south as New Mexico, and as far east as Nebraska. Of the 14 North American species, only a (literal) handful call Oregon home. The pictured pollen is either Pseudomasaris zonalis or marginalis.
Not only do pollens pass on meaty meals for themselves and their offspring, but they’re persnickety about which posies they visit for gathering nectar and pollen. Flowers of choice include beardtongues, borage and tansies. There are also reports of them feeding on mallows and marigolds.
Because of their specific dietary needs, you’ll only find pollen wasps in areas where their favored flora grow. In addition to flowery needs, pollen wasps also need a source for soil and protected spots for building their nests.
Pollen wasps construct nests using a mix of nectar and soil – that’s some sweet mud. Nests are built under rock ledges or sometimes attached to sticks. They’re comprised of between 10 and 14 parallel cells. Each cell is provisioned with a pollen cake and some nectar – sounds yummy. With provisions tucked in, a single egg is laid in the cell and the cell is sealed off with more mud.
The young pollen wasps will fully develop in the nest, then chew through the mud cap at the top of their cell when they emerge as adults.
Pollens have a unique way to carry their pollen provisions as well. They don’t have hair-covered pollen baskets on their legs, or pollen-holding hairs under their abdomens like their bee cousins do. Instead, they carry pollen in their crop much like a bird carries food to store or to feed to their young.
Most of the pollen wasps’ preferred flowers are tubular, so the wasps developed an unusually long proboscis (straw-like mouthpart) to reach the nectar at the base of the flower’s tube.
This gives the pollen wasps an advantage over other pollinators in the area who just can’t get to the nectar source. It also makes pollen wasps key pollinators for the flower species they visit.
For example, the Pseudomasaris vespoides species of pollen wasp specializes in pollinating beardtongue. They pollinate the blowout beardtongue, an endangered flowering plant limited in range to nine counties in Nebraska and one location in Wyoming. Several additional rare beardtongue species rely on pollen wasp pollination. These nifty wasps have an important role in maintaining ecological diversity in the Western states.
Pollen wasps are in flight in Oregon from April through July. So if you see a wasp with clubbed antennae tucking into a totally tubular flower this summer, you can put a checkmark by “pollen wasp” on your list of cool pollinators you have seen.