The Buzz on Pollination Is Not All About Bees: Wasps Are Pollinators Too!

Last time we talked about pollinators (see Is This a Pollinator? Five Types of Pollinating Insects You Can Find in Maryland), we received some questions about wasps. Do they also pollinate? If they do, what do they pollinate? So, let’s talk about wasps!

Besides being super important for controlling pests, since most of them are predators, wasps also can contribute to pollination. In some cases, that pollination is so specialized that plants won’t be able to set fruit if the wasps are not around! But don’t let me get ahead of myself… let’s start from the beginning. What are wasps and how to distinguish them from bees?

Is this a wasp or a bee?

Are you confused about the differences? That’s normal! It’s because bees and wasps are closely related and, in the same way that we tend to look like our close relatives, wasps and bees look similar as well. Like bees, wasps have a lot of diversity, displaying different shapes, sizes and colors. Also like bees, wasps can be social (like hornets or yellow jackets) or solitary (like those that make little mud vases or that dig small burrows in the ground).

Wasps in Maryland
Some wasps from Maryland, which can be sometimes seen visiting white/yellowish flowers. Left: Mason Wasp, Pseudodynerus quadrisectus (photo M. McMasters); center: Ringed Paper Wasp, Polistes annularis (photo: Kieschnick); right: Potter Wasp, Eumenes

Taxonomically, there are two groups of wasps: those that have a wasp waist, and those that don’t. Because the former are the ones that we usually refer to when we think of wasps, let’s focus on those. When we think about those wasps, wasps tend to be less hairy than most bees and tend to fly with their legs extended. The legs of bees are usually wider than those of wasps, and while they fly one can see bees rubbing their legs with one another to transfer pollen, while this will not be the case with wasps. Finally, most social wasps fold their forewings when they are at rest, which makes the wings look long and thin.

bee versus wasp
General morphological differences between wasps and bees. Wasps tend to have thinner legs and are less hairy than bees. Wasps also tend to bend their wings longitudinally when at rest.

What do wasps pollinate?

Wasps are involved in different types of pollination interactions, with many being generalists (they visit many different types of flowers) and some very specialized (involving only a very small number of plants).

Generalist wasps

Even though the vast majority of wasps are predators (they prey on your garden pests!), they also need to supplement their diets with sugar, which is eaten by adults but is also required for the proper development of the offspring. For this reason, many solitary and social wasps visit flowers and collect nectar throughout the flowering season, but in particular during the fall, when other sources of sugar become harder to find. During those visits, they often enter in contact with the flower anthers (the flower part where pollen is presented), and thus passively collect and then transfer pollen when they visit another flower.

Most of these wasps have very short tongues, so they are only able to obtain nectar from flowers that are not too deep. Further, most of these wasps can’t see red colors but can see UV light. Because of all this, most flowers wasps visit are open and not too deep, and white- or yellow-colored. If you would like to attract and observe these pollinators and biological control agents, you can plant flowers of the Apiaceae family (carrot and parsley family) and you won’t be disappointed!

Specialized wasps

In addition to generalist wasp pollinators, there are some very specialized wasps that only pollinate specific types of plants. Next month, we’ll take a closer look at specialized wasps and the ones in particular that are essential for pollinating some delicious fruits — figs!

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park

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