Wasps are often regarded as the terror of the landscape. Now that summer has officially arrived, and the 4th of July is over, gardeners are spending less time outdoors, and more time resting. But when they are outdoors, they do not want to be bothered by wasps. However, this is also the time when our wasp friends are in full swing, providing for their brood.
Do you want to be bothered by wasps flying through the air, going for your slice of watermelon, or landing on those peaches you have not picked yet? No, of course you do not. But we gardeners need to learn to tolerate wasp encounters, for they are for more important that most realize.
For example, did you know that wasps pollinate many flowers? Or did you know that they eat a variety of insects, from caterpillars to spiders? And did you know that parasitoid wasps manage pest populations on a variety of plants by killing insects with outbreaks? In my garden, I tolerate the wasp, because it is a friend.
Wasps and Pollination
They are incidental pollinators. This means that while wasp species are going to flowers for nectar, they are spreading pollen around without meaning to. Solitary, social, and parasitic wasps make up a large percentage of the total number of flower-visiting insects. In general, they have a large capacity to pollinate, and some are better pollinators than bees, but mostly it is not planned by them.
There are a number of species, especially native plants to the Central Great Plains, that are pollinated more heavily by either wasps or bumblebees, than typical bees (honeybees, sweat bees). Often, white flowers are more attractive to some of our common solitary wasps, and I have noticed it many times.
You will discover why growing native plants to attract wasp species is just as important as for other pollinators or beneficials, if not more so. Below is a list of some of the more attractive natives for them. Native plants are highlighted in RED.
- Mountain mints (Pycnanthemum species)
- Tall Sedum (Hylotelephium spectabile)
- Hairy aster (Symphyotrichum pilosum)
- Swamp milkweed (Asclepias incarnata)
- Butterfly milkweed (Asclepias tuberosa)
- Queen Anne’s lace (Daucus carota)
- Rattlesnake master (Eryngium yuccafolium)
- Ornamental onion (Allium species)
- Bonesets (Eupatorium species)
- Yellow coneflower (Ratibida pinnata)
- Goldenrods (Solidago species)
- Calamint (Calamintha nepeta)
- Mints (Mentha species)
- Blazingstars (Liatris species)
- Buttonbush (Cephalanthus occidentalis)
- Culver’s root (Veronicastrum virginicum)
- Rudbeckia ‘American Gold Rush’
Where a wasp lives might be the biggest consideration for whether or not gardeners like them. For it is the social wasp groups that we find the most problems with. These might be the big paper nests, or a hornets nest, or a colony of yellowjackets. No matter which one, if they build their nest in trees, shrubs, or under the eaves of the house or garage, we probably will not like it.
I try to prevent social paper wasps from building on my house, or under the eaves of the sheds, by removing the first nest they build. If their nest is not where it bothers me to walk by, then I leave it alone. Just like with bees, if you leave them alone, they will leave you alone. The problem comes when we do not know they are there. But that is not their fault.
However, many other wasps are solitary and do not make nests that we even see. Some, like potter and mason wasps, make clay or mud homes on the sides of many things, including walls. I try to discourage this, but when you see the prey inside, you will understand why they are important.
What do Wasps Eat?
Now that you have a taste, of what some wasps eat, let us dive in deeper. Adult wasps, that is, the big meanies (my daughter calls them this), mainly eat nectar, some pollen, tree sap, honeydew (aphid excrement), and fruit. Of course, this depends a lot on what is available, as well as the species of wasp. In some conditions, adults may eat eggs of other wasps, or even their larvae.
But the main reason to like the wasp is for the food its larvae consume in the nest. Or what developing larvae of parasitoid wasps eat after hatching from their eggs. This is where pest management comes into play.
Some of the insects that solitary wasp species use as food for their larvae include the following:
- Plant bugs
- Beetles and beetle larvae
- Chafers (June, May, and Japanese beetle)
- Crickets and grasshoppers
- Caterpillars of moths and some butterflies
- Wolf spiders
- Orb weaver spiders
- Gall-forming insects
Together, with birds, beneficial insects, reptiles, amphibians, and mammals, wasps can help make your garden and landscape more ecologically friendly. To do that though, you must limit or remove the majority of synthetic chemicals and pesticides which kill them and their food sources.
Major Types of Wasps
In our gardens, there are 5 types of wasps that I would like to focus on. This is by no means comprehensive. Actually, I am just introducing you to the wide world of wasp species, of which I only know a handful. But go out into the garden sometime and watch them. The prey-hunters are fascinating to watch, as they search flowers and plants for prey.
The wasp types I am going to introduce are the following:
- Spider wasp species
- Potter and mason wasp species
- Paper wasp species
- Parasitoid wasps species
- Scoliid wasp species
I am not going to discuss yellowjackets or hornets, nor many of the unique otherwise wonderful wasp species to be seen. You will have to learn those on your own. For more information on wasps and their life, check out the book: Wasps by Heather Holm.
Spider Wasp Species
Why are we interested in spider wasps? Because they are awesome! If you have even seen a wasp dragging a paralyzed spider across the ground to its nest, then you feel like I do. I used to loathe spiders. When I was young, I had a terrifying experience with a brown recluse spider running down my face while in the bathtub. It has only been in the last 10 years or so that I have learned to love most spiders.
While spiders still give me a little creeping sensation, spider wasps fascinate me. When I first encountered one in my back pasture, it had just paralyzed a large spider and was having trouble dragging it to its nest. I was able to film some of the interaction.
You can hear my excitement in the above video about finding that wasp and its prey.
There are approximately 300 species of spider wasps in North America, and they rarely eat anything else. They are specialized hunters, each species picking a different type of spider to prey upon.
The Eastern Tawny-horned Spider Wasp (In the video above)
One of the more common of this group in the Central Great Plains, they range from Nebraska southward, and from California to Maryland. Unlike other spider wasp species, this one prepares her multicellular nest before hunting her prey. Each cell in the nest is given one large spider, from the class of either wolf spiders or fishing spiders. An egg is laid on the side of the paralyzed spider’s abdomen. And then the wasp covers the nest with soil to hide it.
The Rusty Spider Wasp
In this case, this spider wasp hunts for prey before building her nest. After catching and paralyzing a spider. usually wolf spiders, she drags is to a suitable nesting spot, under a rock or structure. Then she digs a concave, bowl-shaped nest, puts the spider in it, and lays a single egg next to spider’s abdomen. Finally, she covers the nest with soil and debris to hide it.
Potter and Mason Wasp Species
Worldwide, there are more than 3000 species of mason wasps, with about 260 species in North American. Most species nest in pre-existing cavities in the ground, or build their own. They lay a single egg in a cell, suspending it from the ceiling with a thread, then provision the nest with either caterpillars or leaf-feeding beetle larvae. Species that nest aboveground, make nests from mud or sand. Many will use pre-made cavities such as the holes in bamboo or other plant materials, that we gardeners put out for them.
The Smiling Mason Wasp
This species utilizes pre-made or pre-existing cavities or nests left by other wasps, wood-boring insects, or humans. She lays a single egg in each cell, partitioning them off with mud, and stocks each egg with 5 to 8 caterpillars. Prey includes twirler or twig-girdling moths, and concealer moths.
The Fraternal Potter Wasp
This wasp species makes a pot shaped nest from mud and sand, putting it on the underside of a leaf, under the eaves of a house, or on a sturdy stem. She then lays a single egg, hanging from a silken thread, and goes for caterpillars. This species preys upon cankerworms, inchworms, and other geometer moth caterpillars.
The Four-toothed Mason Wasp
Similar to the smiling mason wasp, this species prefers to use a pre-existing cavity left behind by other insects. This is large wasp, and often chooses sites left behind by large carpenter bees. She uses mud and/or sand to partition the cells and seal the final enclosure. Each cell gets one wasp egg and from 4 to 9 caterpillars, depending on the size of the caterpillar. Prey includes fruitworm, crambid, leafroller, snout, grass-miner, twirler, and webworm moths.
Paper Wasp Species
These are the species that most trouble humans in our area. The make horizontal combs of cells, attached to an object. The are colonial in nature, with similar hierarchy to honeybees, wherein one female is the primary egg layer, and her sisters are guards and hunters. They may build their nests under eaves of houses, garages, and sheds, but also in shrubs, trees, and other dry areas.
Prey of Paper Wasp Species in the Central Great Plains
Instead of going through the different species of paper wasps, I am going to show you what they eat. If you have several kinds of paper wasps, then you will have control of caterpillars from the following moth groups.
- Tiger Moths
- Owlet moths
- Geometer moths
- Slug moths
- Silk moths
- Sphinx moths
- Snout moths
- Prominent moths
- Cabbage worm butterflies
Parasitoid Wasp Species
It has been estimated that there may be as many as 650,000 parasitoid wasp species! We do not even know how many there in the United States. There is probably a specific wasp species for every insect pest out there, and maybe more. Most of them are tiny, smaller than 1/4 inch section of a paperclip. But some are quite large and ornate.
Parasitoid wasps mostly lay their eggs inside of the their prey while the prey is yet living. In some cases, parasitoid wasp species actually parasitize other wasps, such as those which produce galls on various trees. One of the best examples of a parasitoid wasp is on tomato hornworms. I usually leave a few hornworms on my tomatoes just to see these parasitoids work.
Scoliid Wasp Species
These wasps are actually a type of parasitoid, laying eggs on the host insect after the female has paralyzed it. There are 560 species of scoliids in the world, and about 20 in North America. Scoliid wasp species are large, and very showy with their colors. I see them often in the garden and am always excited.
The Double-banded Scoliid Wasp
The host of this particular wasp is the larval stage of scarab beetles, which feed underground on plant roots or wood. The female wasp searches for and finds a host larvae, then stings to immobilize it, and lays a single egg on it. After the egg hatches, the wasp larva feeds on the beetle larvae for 1 to 3 weeks, then makes a silken cocoon, and remains underground as a pupa over winter.
The Two-Spotted Blue-Winged Scoliid Wasp
A mouthful of a name right? Anyways, this wasp species is also a parasitoid of scarab beetle larvae, including those of the annoying green June beetle, whose adult form feeds on peaches, apples, and other fruits.
Protecting Wasps and Their Habitat
Wasps are important ecosystem workers, eating caterpillar, beetle larvae, spiders, and much more. Without their aid, even the birds would not be able to keep up with the outbreaks of caterpillars. And we gardeners may try to resort to chemical pesticides for control. It would be our mistake.
When we have an outbreak of pests, such as aphids, which reproduce quickly, we often resort to chemicals. What happens is a nightmare for all. We kill the pest, or rather, 98% of it, and all of the predatory and parasitoid insects. Then the 2% of resistant aphids grow and reproduce quickly, overwhelming plant defenses. And, without any beneficials to help control them, the plant dies quickly.
We need to work more with the natural forces of good that were given to us, and not fight against them. Plant a species rich garden and landscape. Leave brush piles, leaves, and natural habitats alone for wildlife. Do not destroy the soil food web with tillage, chemicals, or synthetic fertilizers. Let nature do the hard work or pest control for you.
I love wasps. There are so many which fit into so many different ecosystems, and they fit into our gardens as well. I hope this gives you a better understanding of why they are important friends in the garden, and not our foes.