Wasps in the Garden: Allies for a Healthy Garden Ecosystem

Wasps in the garden might make many of us feel a bit nervous. But did you know these insects are actually our allies? Wasps play a crucial role in keeping our gardens healthy and thriving. They're not just pesky stingers; they're beneficial insects that help control pests and pollinate plants. 

So, what makes wasps so special? For starters, they're excellent pollinators, just like bees. They also have a big impact on pest control, munching on aphids and other harmful bugs. This article will explore the different types of garden wasps you might encounter, how to make your garden more welcoming to these helpful critters, and tips for living safely alongside them. 

The Vital Role of Wasps in Garden Ecosystems

Wasps play a crucial role in pollination, making up 15 percent of flower-visiting insects worldwide. While they may not be as efficient as bees due to their smooth bodies, wasps still contribute significantly to the pollination of various plants. They are attracted to nectar and carry out a useful amount of pollination in gardens .

One fascinating example of specialized pollination is the fig wasp. These tiny insects are the sole pollinators of fig trees, making them indispensable to the fig-growing industry. In fact, researchers have identified 164 plants that rely exclusively on wasps for pollination, including figs which are vital for the survival of 1,000 tropical bird and mammal species .

Wasps are natural pest controllers, playing a crucial role in maintaining garden health. They have voracious appetites for various garden pests, including aphids, flies, and caterpillars. Social wasps, such as paper wasps, feed these insects to their larvae, effectively controlling pest populations throughout the summer.

Many solitary wasps also hunt and kill insects to feed their young. Some parasitic wasps, like the minuscule Encarsia formosa, have long been used to manage whitefly populations in greenhouses. Braconid wasps lay their eggs on tomato hornworms and other caterpillars, providing an effective form of biological pest control .

Wasps contribute significantly to biodiversity in garden ecosystems. They are essential for maintaining ecological balance by controlling populations of various insects. Without wasps, many leaf and seed-eating insects would go unchecked, potentially leading to reduced biodiversity.

Wasps also support plant diversity by pollinating a wide range of flowers. They are particularly attracted to simple, shallow flowers from plant families such as carrot relatives, asters, mints, and milkweeds. By helping these plants reproduce, wasps indirectly support other wildlife that depends on these plant species for food and habitat.

Common Wasp Species Found in Gardens

There are approximately 103,000 species of wasps in the world, with only 1,000 of these being social, while the others are either solitary or parasitoid .

Social Wasps

Social wasps, belonging to the Vespidae family, live in colonies and build shared nests. These nests can house anywhere from a few dozen to thousands of wasps. The most recognizable social wasps are yellowjackets and hornets, known for their bright yellow and black coloration. These wasps are often found building honeycomb nests under the eaves of houses, in trees, shrubs, or under patio furniture. Social wasps feed on a wide variety of insects such as flies, caterpillars, and beetles, making them valuable for pest control.

Solitary Wasps

Solitary wasps make up the majority of wasp species and are less well-known than their social counterparts. These wasps do not build colonies and are generally less aggressive. Some notable solitary wasps include:

• Great Black Wasp (Sphex pensylvanicus): Also known as the "katydid hunter" or "steel-blue cricket hunter," this wasp feeds on young crickets and katydids.
• Thread-waisted Wasp (Ammophila procera): This species builds underground nests in sandy soils and eats caterpillars and other insects.
• Cicada Killer Wasps (Sphecius speciosus): These large wasps prey on cicadas and are not typically a threat to humans.

Parasitoid Wasps

Parasitoid wasps have a specialized life cycle where they lay their eggs inside or on other insects. Some interesting examples include:

• Braconid Wasps: These small wasps, often mistaken for flies, lay their eggs deep inside tree holes using a long needle-like structure.
• Ichneumon Wasps: Also known as Darwin wasps, they use their long ovipositors to penetrate tree bark and lay eggs in the larvae of moths or beetles.
• Pelecinid Wasps: The American Pelecinid Wasp (Pelecinus polyturator) lays its eggs in Japanese beetle or June beetle larvae in the soil.

These parasitoid wasps are excellent for pest control, as they often target specific harmful insect species. For example, three parasitoid wasp species have been released in Minnesota to help control the Emerald Ash Borer.

Creating a Wasp-Friendly Garden

To attract wasps and other beneficial insects, gardeners should focus on planting a diverse range of flowering plants. Wasps are particularly drawn to flowers in white, purple, blue, and yellow. Umbellifers, such as plants from the Apaceae family (carrots, parsley, parsnip, wild carrot, and false queen anne's lace), are especially attractive to wasps. These flowers have clusters of tiny cup-like blooms that allow larger insects to walk and quickly consume nectar from multiple shallow flowers.

Buckwheat is another excellent choice for a wasp-friendly garden. This quick-growing plant from the rhubarb family offers high-nectar flowers and is associated with promoting beneficial wasps. It's great as a filler plant and can flower in as little as 4 weeks. Other plants that attract wasps include sweet fennel and spearmint, thanks to their colors and nectar .

Water plays a crucial role in attracting wasps to the garden. Wasps need water to make and maintain their nests. When watering plants, especially cacti and succulents, wasps may come down from their nests to collect water droplets. To provide water sources without disturbing wasps, gardeners should:

Creating an environment that meets wasps' needs is essential for promoting their populations in gardens. It's important to allow some areas of the garden to remain undisturbed, as wasps prefer to build their nests in quiet, sheltered spaces. Stem-nesting wasps, for example, create nests in dry stems from the previous growing season. To support these wasps:

• Leave stems standing over winter rather than cleaning up in fall
• Allow some plant stems to remain at an angle, which helps keep rain out
• Use pruners to create topless stems that wasps can lay eggs in
• By implementing these strategies, gardeners can create a welcoming environment for wasps, harnessing their natural pest control abilities and supporting a diverse ecosystem in their gardens.

Coexisting Safely with Wasps

Wasps are territorial insects that play a crucial role in garden ecosystems. They typically only attack when disturbed or when their territory is threatened. Wasps communicate danger through various signals. When feeling threatened, they may buzz loudly, fly in an agitated manner, raise their abdomen, or extend their stinger. These behaviors indicate that the wasp is preparing to defend itself. Additionally, wasps release alarm pheromones that can trigger defensive behavior in nearby nestmates.

To minimize wasp presence around your property, it's crucial to take preventive measures, especially during spring when queens become more active and start building nests. Here are some effective strategies:

• Close off cracks and gaps in doors, windows, and other areas of your home
• Keep garbage bins and compost piles tightly sealed to avoid attracting wasps .
• Peppermint oil mixed with water and dish soap in a spray bottle can be an effective deterrent for places you don't want the wasps to nest.
• Regularly clean up fallen fruit, food scraps, and sugary drinks that might attract wasps to areas you don't want them, like around your house.

Dealing with Wasp Encounters

If you find yourself in close proximity to wasps, it's essential to remain calm and follow these guidelines:

1. Wasps are sensitive to movement, so avoid flailing or running, which may provoke an attack .
2. If surrounded by wasps, move away with your eyes closed and head down, covering your face if possible .
3. If being swarmed, run to the nearest building or vehicle for protection .
4. Don't try to hit the wasps, as this will only make them more aggressive .

By understanding wasp behavior and taking appropriate precautions, we can coexist safely with these beneficial insects in our gardens and outdoor spaces.