Gardening to attract beneficial wasps.

 

Beneficial wasps are worth attracting to the garden because they are beautiful and interesting to watch. They increase diversity in the garden and they keep many insect populations in check. Any integrated pest management scheme or permaculture guild should include plants for these wonderful creatures because it is easier to use them as biological controls rather than using pesticides.

Insects are beneficial by acting as predators, parasites or parasitoids. With beneficial wasps, either the egg is laid directly on the prey, in the prey or the prey is paralysed and carried to a chamber where it left for the larva upon hatching. Parasitoid wasps are differentiated from predator wasps by their behaviour. Parasitoids lay their eggs on a single insect host in situ whereas predators may carry or drag the prey to a chamber where the larva will hatch and feed. Predator wasps may also furnish their offspring with more than one food item.

In insects, it is the larval stage in which the greatest amount of consumption occurs. Some larvae increase their bodyweight by over a thousand times between the moment they hatch and the pupal stage of the life-cycle. Larvae such as ladybird or hoverfly larvae are predators that actively hunt down their prey. Parasitoid wasp larvae are already on or in their host when they hatch. Parasitoids feed off living animals usually attacking the non-essential organs first before moving onto the body parts that will result in the death of their prey. This strategy, ensuring that the prey remains fresh to eat for the longest period of time, is commonly employed by beneficial wasps.

	The caterpillar of the tomato hornworm is covered in cocoons from the parasitoid braconid wasp, Cotesia congregata. At this point, the damage to the caterpillar is already done as it is the larva of the wasp that eat through the insides of a caterpillar. The cocoons protect wasp during the pupal stage of the life cycle.

 

Fossorial wasps are predatory and have an excellent memory that allows them to map their surroundings. They may catch their prey hundreds of feet away from the hole they dug and have to be able to find their way back while dragging their prey along the ground. Obviously, to have beneficial wasps make your garden their home you have to provide them with larval food. This means that you have to tolerate the damage done by a large range of herbivorous insects. As mentioned elsewhere on this site, the damage is usually limited if the garden is ecologically balanced and not noticeable unless a close inspection is carried out.

You are not likely to see the larvae, because they are usually hidden in the following locations: within logs, dead trees, hollow stems; in the ground; or in the self-constructed nests. What you will see are the adults obtaining nectar and looking amongst the flowers for caterpillars and other insects to feed their young. For more ideas on providing shelter for beneficial wasps, read about shelters for bees. Many of them will use the same type of constructions. A bare patch of soil free of disturbance will be appreciated, especially if the soil is sandy.

 

	Beneficial wasps, such as this Great Golden Digger wasp spend a large amount of their time collecting nectar.

Adult beneficial wasps often feed on nectar and are important pollinators in their own right. They need the nectar as a source of energy to go about their daily routines. Planting the right perennials will draw them into your garden (see below for a list). Provide the wasps with a shallow water bath with some stones. Many of them appreciate a drink on a hot day. A bird bath will help both the wasps and the birds. Once they have learnt its location, you will observe them flying in a straight line from the flower beds to the bath.

	Wasps do not have pollen baskets on their hind legs like bees. Instead, the pollen can accumulate on the body hair. In the picture shown here, the insect has clearly pollinated plants with their reproductive parts located in the upper part of the flower such as Monarda punctata. These flowers are described as nototribic.

Plants to attract beneficial wasps include:

Boneset	Calamints
Carpenter's square	Mountain mints
Clethra alnifolia	Cutleaf coneflower
Flat topped white aster	Flowering spurge
Goldenrods (particularly Euthamia sp.)	Heath aster
Milkweeds	New Jersey Tea
Rattlesnake master	Spotted bee balm
Oregano, mints and many other herbs.

Now just in case you are wondering, these wasps do have big stingers, but they are not aggressive. If you squeeze one in your hand, you will be stung. If you brush one accidentally, they will just fly away. The vast majority stinging incidents involve common wasps known as yellowjackets in North America. The workers of these particular wasps may feed on nectar in the latter part of the summer, but planting flowers will not attract them particularly. Yellowjackets do however feed on dead meat so your barbecue may bring them in instead. It is worth remembering that yellowjackets do a lot of good by removing many plant pests and by providing pollination services. Bald-faced hornets look similar to yellow jackets except that they are typically black and white.

	Even from a distance, it is possible to determine what type of wasp has made this nest. Since bald faced hornets pollinate flowers and remove insect pests, they are worth keeping in the garden. Bald faced hornets are mostly black with some noticeable white patches on the face and the tip of their abdomen. Yellowjackets tend to make nests in the ground or inside structures.

	This photograph was taken at close range without incident. One should always be cautious when dealing with social wasps of any sort, but there is no need to rush out to get insecticide. If the nest is out of reach of children, then it is unlikely to cause an issue. I get at least one nest around my house every year.

Paper wasps are the most common nest builders in the vicinity of a house. They will find holes in walls and they commonly nest in an eavestrough. The nest has cells that are visible and point downwards. The wasps hang upside down to move in and out of the cells. Guards are common and they will spy your every move when you are close by. The nests are about 10cm (4 inches) in diameter or less and may house up to about 200 wasps. The most common paper wasp in the East is an introduced species called Polistes dominula, the European paper wasp. They are particularly fond of human habitation and are more aggressive than other wasps. Watch out for them when you clean your eavestrough. They are an invasive species and there are good ecological reasons for removing any nests that you find (at your own risk!). They use spaces that could be used by native paper wasps or by birds if the cavity is large enough. They eat more species than other paper wasps, so they could be having a negative effect on the wildlife in your garden.

	These wasps resemble yellow jackets to a novice and often get easily confused. The easiest way to make a positive id is to check out the antennae which are bright orange.

Polistes fuscatus is one of the species that has been widely displaced by the European paper wasp. It is larger and it is really quite beautiful for a wasp.

	Polistes fuscatus has noticeable patches of red and yellow on its flanks. In Ontario, it is still fairly common despite the introduction of the European paper wasp. Its future remains to be seen.

Potter wasps and mason wasps are also common in gardens. Some nest on the outside walls while others nest inside hollow broken stems or in the ground. Many of them use clay to build their nests. They are fond of Boneset, a plant that is excellent for attracting some of the more unusual wasps into the garden. They are related to yellowjackets, but they are solitary and not aggressive.

	Eumenes fraternus on Common Boneset

 

Thread-waisted wasps include the Great Black Wasp (Sphex pensylvannicus) and the Great Golden Digger Wasp (Sphex ichneumoneus). These wasps paralyse insects from the order of grasshoppers and drag them back to their tunnels which are made by individual females. Their population size is limited by their food supply as well as a range of kleptoparasites. This includes some birds that steal their prey from them while they are on the way back to the nesting site and various flies that hang around the nesting site. They occur frequently in gardens, especially if you plant monarda sp. or milkweeds. Like other insects that dig chambers, these insects help to aerate the soil.

	The Great Black Wasp is not just black. Viewed from the right angle, one can see a beautiful Tyndall blue in the wings. They are easy to confuse with Podalonia luctuosa, which feed cutworms to the larvae.

	The Great Golden Digger Wasp is hard to confuse with other wasps. It is closely related to the Great Black Digger Wasp but its size, half-orange abdomen and orange legs are unmistakeable.

Bee wolves

Bee wolves eat bees and other wasps so they are not really that beneficial. Their presence though does indicate that there are plenty of bees in your garden to support food chains and this is a sign of general garden health. Their similarity to other beneficial wasps is enough for them to be included here. They hunt for many different species of bees and some wasps and they construct small underground nests to house and feed their larvae.

	Philanthus gibbosus pollinating Monarda punctata

 

Bald Faced Hornets

Bald faced hornets are much maligned by being grouped with the closely related yellowjackets. However, their behaviour is far less aggressive and they are far more important as pollinators. They are important controls of herbivorous insects in the garden and they also are great for pollinating certain plants like Milkweeds. During the winter, the queens can be found hibernating under logs.

	Bald-faced hornet on Swamp Milkweed

Sand Wasps

Exactly as their name says, they nest in bare sand. Bicyrtes quadrifasciatus is easy to confuse with similar Bembix species, but its white bands become more widely spaced towards the distal end of the abdomen. They feed leaf footed bugs and stink bugs to their young while collecting nectar for themselves. They will return to a nest hole several times and each time they leave the entrance they cover it up with some sand. Bembix sp. have nearly continuous white bands and feed on flies.

	Bicyrtes quadrifasciatus on Eupatorium perfoliatum

Cicada Killer Wasps

I have not bothered to show the full dorsal surface of the cicada killer because they are easily recognised by the brown tinted wings, the red eyes on the white face, and their immense size for a wasp. They grow up to 2 inches (50 mm). It is fair to say that a few of these might look very intimidating, but, the males do not sting and females have no propensity to sting humans even though they have a stinger. Considering their own size and the size of their prey, their excavations are quite large. Each cell may be provisioned with several cicada and these wasps tend to congregrate their nests in bare patches of sandy soil.

	Cicada Killer Wasp - Sphecius speciosus

Thread-waisted wasps

Eremnophila aureonotata and similar wasps such as Ammophila sp. are caterpillar hunters. Eremnophila is a fossorial wasp that specialises in prominent moth caterpillars. Eremnophila is known for hiding the nesting entrance with leaves. Although the wasps are quite large, they cannot sting humans.

	Eremnophila aureonotata on Pycnanthemum virginiana

These particular wasps are easy to recognise with their silver faces and with small patches of silver or gold on the thorax and propodeum. They spend a long time on nectar rich flowers in the garden such as this mountain mint.

 

	Eremnophila aureonotata, with their silver faces, are frequently observed in the act of mating.

Ammophila are quite easy to recognise due to the orange patches on their abdomen combined with a long straight petiole that connects the abdomen to the thorax. They also dig burrows and stock them with caterpillars.

	Ammophila sp.

Grass-carrying wasps

Isodontia are known as grass-carrying wasps. Isodontia mexicana is a common wasp in suburban gardens. You can identify them easily because they are all black and the waist connecting the abdomen to the thorax is quite straight.

	Isodontia mexicana carrying the pollinia of Milkweeds

Each larva is sealed off using dead blades of grass and is provided with 2 or three grasshoppers to eat.

 

 

	The larva is on the right-hand side of the cell.

 

Mason wasp

Monobia nests in holes in wood or empty bamboo canes. They also will also take advantage of abandoned nests. They feed caterpillars to their larvae and divide each cell with mud.

	Monobia quadridens - Mason wasp

Pelecinid wasp

The distinctive Pelecinus polyturator is a very large wasp indeed, reaching up to 3 inches (70 mm) in length. The larvae feed on the same scarab beetle larvae that damage grass roots and the female uses her long ovipositor to lay eggs on hosts in the soil. The species is unusual in a couple of ways. It is parthenogenetic. The females can reproduce without the need to mate and are therefore far more common than males. The species also exhibits sexual dimorphism with the females being much larger.

	Pelecinus polyturator (female)

Pimpla pedalis

The picture shows a female Pimpla pedalis with what looks to be a large stinger. Actually, it is just an ovipositor. Braconid wasps and ichneumon wasps, such as Pimpla pedalis, retain the use of an ovipositor (even if they can sting as well). In this respect, they differ from many of the other wasps shown here in which the ovipositor has evolved to become merely a device to sting. They help to keep moth larvae under control.

	Pimpla pedalis

Scoliid wasp

Scolia dubia has a distinctive red abdomen with two large proximal yellow dots. They also feed on scarab beetles in the soil. The females dig down into the soil to find a beetle larva, which is then partially paralysed and onto which she lays an egg. She then constructs a nest cell around the larva. This wasp can help to control Japanese beetles and they should always be welcomed in a garden.

	Scolia dubia on Pycnanthemum muticum

Myzinum quinquecinctum

The five-banded tiphiid wasp has only five bands if it is a female. The species exhibits an obvious sexual dimorphism with males having six bands and an abdomen that is more slender. These wasps have similar feeding habits to Scolia dubia except that do not construct nest cells.

	A female Myzinum quinquecinctum

 

Mud Dauber Wasp (Sceliphron caementarium)

With its black and yellow legs, long pedicel and a yellow segment at the base of its antenna, this wasp is distinctive. It creates vertical tubular nests out of mud on the side of buildings. It provides larva with spiders.

 

	Sceliphron caementarium

 

Square-headed wasps

These wasps are often seen on flowers but are not quite as common as some of the other wasps mentioned here. They are known for capturing adult flies, paralysing them and carrying them back to their nests. A lot of Crabronine wasps like the Ectemnius sp. shown here will nest in excavated logs.

	Ectemnius continuous

 

Yellowjackets

These are the wasps that are most likely to sting you. They get aggressive when defending the nests and they may also get more aggressive around the barbeque! I do not find them particularly dangerous when they are out looking for prey and stop to drink some nectar. The benefit of these wasps is the same as most of the other mentioned above. They keep pests under control and they pollinate the flowers.

	Vespula maculifrons pollinating upland white aster.