Seven-spot ladybird: a beneficial insect for controlling aphids in the garden

The seven-spot ladybird is one of the most well-known ladybirds in the UK. Ladybirds eat aphids and other garden pests and are therefore among the first beneficial insects ever to be used for biological pest control.

Most gardeners are familiar with aphids (Aphidoidea), which are a type of pest that feed on the sap of our beloved plants. Luckily for us, aphids have a few natural enemies, one of them being the ladybird. Read on to find out more about the seven-spot ladybird (Coccinella septempunctata).

Seven-spot ladybird: characteristics and way of life

The seven-spot (or 7-spot) ladybird reaches five to eight millimetres in length and, like all insects, has six legs. As the name suggests, it has seven black spots on its orange-red wing cases. The seventh dot, which is separated by the two wings and flanked by two bright, elongated spots, is a special identifying feature of Coccinella septempunctata. There are also two white spots on the front part of the chest, as well as on the head between the two black eyes. The seven-spot ladybird has two antennae with which it can “smell” and feel. Unlike other ladybird species, seven-spot ladybirds all look more or less the same – it is rare for members of this species to deviate in terms of wing case colour or how many spots they have.

Coccinella septempunctata are polyphagous, meaning they have a very broad diet. Besides aphid species, which are necessary for seven-spot ladybird larvae’s development, the seven-spot also consumes other things such as thrips (Thysanoptera), leaf beetles (Chrysomelidae) and even their own species’ eggs.

Seven-spot ladybirds are the third most common ladybird species in the UK after the invasive Harlequin ladybird and the two-spot ladybird. They often overwinter in colonies on the damp ground, surrounded by leaves, grass or moss. Once temperatures rise, the mating season begins. Egg-laying starts at the end of April, with a female laying up to 400 eggs on parts of plants that are usually already infested with aphids. A few days later, the first seven-spot ladybird larvae hatch and predatorily attack the aphids. After three moults, the larvae pupate and about a week later a seven-spot ladybird emerges.

In the UK, 7-spot ladybirds usually only produce one generation per year, whereas in more southern countries, two broods per year is quite common. In India, as many as 15 to 20 generations have been observed. Each seven-spot ladybird specimen lives for about 12 months.

Coccinella septempunctata’s preferred habitat changes throughout its lifetime. The larvae grow up protected in the herb layer. The beetles migrate to shrubs for mature feeding and then overwinter on trees, in houses or on the ground. In spring, they return to lay their eggs where their larvae can grow up sheltered and close to the ground on herbaceous plants.

7-spot ladybirds feed mainly on aphids. If aphid populations become scarce, Coccinella septempunctata will also feed on pollen and fungal spores if necessary or migrate to the next aphid colony. Their activity depends on the weather. At 18 °C and without rain, the eggs develop into a pupa within 2 months. At 25 °C, on the other hand, it takes only 15 days.

Seven-spot ladybird as a beneficial insect against aphids

Once temperatures hit 18 °C, you can use seven-spot ladybirds for a natural and effective aphid control method without the need for synthetic pesticides. Here are a few things you need to bear in mind for a successful application of seven-spot ladybirds.

Successful use of seven-spot ladybirds:

• Do not apply chemical pesticides for 6 weeks in advance.
• If necessary, remove excessive numbers of ants before application.
• Ensure the temperature at the control site is at least 18 °C.
• Use in closed spaces such as conservatories, rooms and greenhouses – this is much more effective than using outdoors, where the beetles inevitably migrate.
• In good conditions, you will see results after just a few days.

Tip: Beneficial insects like ladybirds are sensitive to pesticides. However, some pesticides are less harmful to ladybirds or are broken down so quickly that you do not need to wait as long before applying the beneficial insects. Those based on rapeseed oil or potash soap or products made with neem oil can be used a week before the beneficial insects arrive to decimate the pests.

Aphids and ladybirds: How do seven-spot ladybirds control aphids?

Seven-spot ladybirds purposefully lay their eggs on plants that are already infested with aphids. The freshly hatched Coccinella septempunctata larvae are very hungry and, depending on the aphid species, eat up to 1200 aphids during their development period, while adult seven-spot ladybirds only eat up to 150 aphids per day. Young larvae of the seven-spot ladybird usually also consume smaller prey by biting them and then sucking them dry. Larger larvae and adult beetles, on the other hand, can chew their food completely.

How to use seven-spot ladybirds for aphid control

Here is how to use ladybirds as beneficial insects:

• 150 beetles are enough to control about 10 m² of infested area.
• Place the plants as closely together as possible so that the seven-spot ladybirds can easily migrate from one plant to the next.
• If possible, apply the ladybirds in the evening after receiving them or the following morning.
• Open the packaging at the application site.
• Carefully remove the pieces of foil containing the eggs and place them at the infested site.
• Alternatively, attach with clothes pegs.
• Place the ladybirds as close to the aphids as possible.
• Make sure it is at least 18 °C and avoid places with strong sunlight.
• Wait, observe and check the success of control after approx. 3 weeks.

Seven-spot ladybirds are not the only animals that can help combat pests. In the following article, we present 10 beneficial insects in the garden that you should be aware of and encourage in your garden.