warning as strange moss appears on garden plants

Scientists are asking people to report sightings of the peculiar moss, which is linked to the spread of a deadly plant disease

As the temperature climbs, many of us will be spending more time outdoors and in our own gardens. However, households are advised to pay attention to anything unusual among their flower beds.

READ MORE: 12 garden diseases and disorders – and how to fight back

Clumped on the leaves and stems of plants, you may have come across a moss-like substance – the telltale calling card of spittlebugs.

Although a harmless and common insect, the moss they produce is linked to a deadly plant disease and scientists are asking for the public’s help in monitoring its spread.

What is a spit?

Bedbugs live on many different plants, including chrysanthemum, dahlia, fuchsia, lavender, rosemary, rose, and willow.

They are most active from May to July and there are 10 different species of spittlebug in Britain alone. Although they feed on plants, they do not drain enough nutrients from the sap to harm them and they pose no risk to humans.

The white foam they often leave on plants is known as cuckoo spittle or spittlebug, and spittlebug nymphs cocoon in it for protection from predators. But why do scientists track their habitats?

Image: Ihor Hvozdetskyi / ShutterstockThe telltale moss balls are usually found on the leaves and stems of plants.
Image: Ihor Hvozdetskyi / Shutterstock

Why is cuckoo spit dangerous for plants?

The moss itself isn’t inherently dangerous, but stink bugs can carry the bacteria Xylella, which causes a deadly plant disease that could wipe out over 650 UK native plant species.

According to the ERS, the disease is spread by insects that feed on the xylem of plants and cause symptoms such as leaf scorch, wilting, dieback and plant death.

The European Commission considers Xylella “one of the most dangerous plant bacteria in the world” and the disease has devastated olive groves in Italy in recent years, as well as citrus fruits and vineyards.

Although it has yet to be found in the UK, its recent spread across Europe has led the horticultural industry and UK government to take action to try and prevent the arrival of Xylella.

If the bacteria were discovered on UK soil, all plants within a 100m radius would have to be destroyed and a five kilometer plant quarantine imposed for up to five years.

What does the peekaboo brooch look like?

In late spring and summer, you may notice small, bubble-shaped spots of moss on plant leaves and stems, where spittlebug nymphs feed. Small insects will be up to a quarter inch long.

Image: Reality Pictures/ShutterstockBedbugs vary in color from pale brown to black. Image: Reality Pictures/Shutterstock

After about a month, the nymph molts into an adult insect that leaves the spit. Adult stink bugs can fly and jump impressive distances from plant to plant.

What to do if you spot spittlebugs in your garden

First, remember that spittlebugs are not pests and do not need to be removed or treated with insecticides. As the RHS indicates, these insects must be tolerated as part of the biodiversity of your garden.

You can gently pry them off the plants if you have to, with water or by hand. Although they pose no threat to your plants, you will help scientists by monitoring your garden for signs of insects.

The RHS, in partnership with other organizations, founded the BRIGIT project, which focuses on monitoring and responding to the threat of Xylella. You can submit spitting observations from your backyard or the countryside through their online survey.

This will help the UK develop a plan to respond to an outbreak, should Xylella bacteria arrive in the UK.

READ MORE: 13 Common Garden Pests and How to Treat Them

Featured Image: Kongwit Photographer/Shutterstock