Enemies of ladybirds

The bright colours of many ladybirds are to warn potential predators of their distastefulness (aposematism). They exude a yellow substance (reflex blood) when attacked which is rich in toxic alkaloids. Despite this, ladybirds do have enemies.

A 7-spot ladybird and the cocoon of its parasitoid wasp

A 7-spot ladybird and the
cocoon of its parasitoid wasp
Dinocampus coccinellae
(photo: Mike Majerus)

A female phorid ovipositing

A female phorid ovipositing
into a 2-spot ladybird pupa

Sexually transmitted mites

The underside of a ladybird's elytron
infected with the sexually transmitted
mite Coccipolipus hippodamiae
(photo: Emma Rhule)

Predators

Some birds, such as swifts and swallows, which feed on the wing are immune to the defensive chemicals of ladybirds. Ladybirds are also attacked and eaten by some spiders, some of the larger predatory beetles and true bugs (Hemiptera), and their eggs and larvae occasionally fall prey to other species of ladybird and to lacewing larvae.

Parasitoid wasps and flies

Several species of wasp and true fly lay their eggs on or inside ladybird larvae, pupae or adults. When the eggs hatch, the larvae of these parasitoids feed inside their ladybird host, exiting when fully-fed to pupate and emerge as adults outside the ladybird, which dies as a result. These parasitoids include the wasp Dinocampus coccinellae (Braconidae) - see picture, at least one species of scuttle-fly (Phoridae), and a tachinid fly.

Mites

Some mite species affect ladybirds, including sexually transmitted mites in the genus Coccipolipus, which cause sterility in some ladybirds.

Pathogenic fungi

The soil dwelling fungus Beauveria bassiana is pathogenic to some ladybirds species. The fungus produces infective spores which germinate and then penetrate through the insect cuticle. This fungus then proliferates within the host until it has utilised all available host resources at which stage it erupts back through the host cuticle and produces more infective spores. Fungi in the genus Laboulbeniales also affect some ladybirds

Male-killing bacteria

Some female ladybirds (including harlequins) are infected with a male-killing bacterium (Spiroplasma), which kills male but not female embryos. This male-killing causes an imbalance in population sex ratios in some parts of Asia. Work is currently in progress to find out whether any of the harlequins that have arrived in Britain are infected with this sex ratio distorter.