What are Hairy Flower Wasps?
Hairy Flower Wasps are native to Australia. They belong to the wasp family Scoliidae and occur throughout most parts of Australia. They are large wasps with body lengths that usually measure from 1 to 3 cm although some can reach almost 4 cm in length – and that is large for an Australian wasp.
There are two main groups of Hairy Flower Wasps that occur within Victoria.
- The flower wasp most frequently seen in the back yard of most Victorians is. These wasps will most likely be seen flying just above ground level and in particular flying near or around compost heaps, wood heaps or dead stumps of trees. They can be easily recognised by:
- their wings, which have a distinctive, metallic, blue-purple sheen
- their size, which is usually 2.5 to 3.0 cm
- their colour, which is predominantly black
- their wing veins, which do reach the margin of the wing
- their antennae, which are short.
The second group is called Campsomeris. These wasps will also be seen flying at ground level in similar situations to Scolia soror. Campsomeris Flower Wasps are easily recognised by:
Source: Museum Victoria
- their size, which is up to 3.0 to 4.0 cm
- their colour, which is predominantly orange-yellow
- their wings, which are also yellow in colour.
Campsomeris Flower Wasp
Source: Museum Victoria
Why are they called flower wasps?
Like most insects that visit flowers, Hairy Flower Wasps drink nectar. Nectar provides them with food energy in the form of sugars that they use to power their wing muscles.
Flower wasps are frequent visitors to flowers and due to their size and colour, are extremely obvious when sitting on a flower.
What are they doing in my backyard?
Adult female flower wasps are designed to dig. They are large and powerful wasps. The female wasps are often seen visiting compost heaps or wood piles or flying around the dead stump of a tree. They are searching for scarab beetle grubs (such as the Christmas beetle group) in the ground and are quite capable of digging into compost heaps or saw-dust of a tree stump to find beetle grubs.
A Flower Wasp visiting a flower
Photographer: Otto Rogge. Source: Otto Rogge Photography
Most wasps feed on other insects. Some, like the paper wasps catch their prey and kill it immediately to feed their young. However, many wasps have developed the technique of paralysing their prey and laying an egg inside the host. The hatched larva then feed inside the living host. Flower wasps are one such group of wasps.
Having located a beetle grub, the female stings and lays an egg inside it. The sting from the wasp does not kill the beetle grub but only paralyses it. There is a good reason why the female wasp does not kill the beetle grub. If the sting were to kill the beetle grub, then its tissue would immediately start to rot and decompose. When the wasp egg hatches inside the paralysed beetle grub it is surrounded by living tissue – the food that it needs to eat. The developing wasp larva knows which parts of the beetle grub to eat first to prolong the grub’s life for as long as possible; thus maximizing the chances of complete development of the wasp larva.
What are parasitoids?
An insect that slowly kills its host, usually near the end of the larval development is called a Parasitoid. This contrasts to the term Parasite in which the host usually is not killed.
Parasitoids are important natural population regulators in the insect world.
Do they live in colonies?
No – flower wasps are solitary and do not make a nest or form a colony. If you see several flying around a compost heap or tree stump it simply means that several wasps have found the area.
Do they sting and if so what will happen?
Yes – flower wasps do have a well developed sting. However, unlike a honey bee or a paper wasp, flower wasps do not have a nest or colony to protect, and therefore are not aggressive.
Importantly, they will not attack people for just being near where they are searching for food.
The only way you could get stung by a flower wasp is to accidentally stand or sit on it. This can occur as the flower wasps fly at ground level looking for beetle grubs.
To our knowledge, no one has ever had a problem with the sting of a flower wasp other than the pain of the sting itself. Usually the application of a water-ice pack placed on the sting site will quickly reduce the pain and swelling. Unlike the honey bee, the barb of the sting will not remain in the victim’s skin.
How can you or discourage them?
To discourage the flower wasp, you would need to remove it’s habitat from your area. However, there are a number of good reasons to leave it be.
- Flower wasps are native to Australia
- Flower wasps are solitary insects so do not develop a colony like a honey bee or European wasp
- Flower wasps are not aggressive wasps
- Flower wasps are useful for maintaining the populations of other insects – your own natural spray can!
- Flower wasps have an amazing life cycle
- Flower wasps will rarely sting you; if stung, the only consequence will be the pain of the sting.
Enjoy your local fauna!