Ladybirds are members of the beetle family Coccinellidae, and are predatory insects that control populations of aphids in gardens and in fields. Ladybirds, or ladybeetles/ladybugs, are well recognizable insects that are adored for their beautifully spotted bodies, but there are several things about ladybirds that one should know…
1. Ladybirds practice cannibalism
When food is scarce, ladybirds may resort to eating whatever soft-bodied organism is nearby, including other adults, pupa, larvae and even eggs of other ladybirds. Even the ladybird larvae which are the first to emerge eat their future siblings (unhatched eggs), but some of these have not even been fertilised by the adult, presumable for the purpose of giving the first hatching young more of a chance of survival.
2. Ladybirds bleed from their knees when threatened.
Ladybirds signal their toxicity using aposematic coloration (black spots upon red, white spots upon orange…), but they have another defence. When startled, ladybirds will seep toxic and foul-smelling hemolymph (rich in alkaloids) from its leg joints, leaving yellow stains on the surface below it. Predators are deterred by the prospect of eating such a rank smelling and bad looking prey item, and are repulsed enough to search elsewhere.
3. Ladybirds are highly promiscuous
Ladybirds are so promiscuous that in 2-spot ladybirds clutches often contain eggs fertilised by more than 3 different males. Because of this, ladybirds can transmit mites that feed on blood below the elytra to one another during mating- an STD! A mite-infested ladybird can reduce the size and viability of clutches. And as expected the higher the number of mating partners, the more mites a female ladybird will catch- sometimes up to 81 mites!
4. Ladybirds aggregate in the winter to hibernate
When temperatures fall and days become shorter, ladybirds seek shelter in protected locations- under leaves, behind bark and even in houses. Thousands of ladybirds may gather in one location to take advantage of the collective heat for energy conservation.
5. A ladybird may eat as many as 5000 aphids in its lifetime
Aphids are beneficial predators that control populations of pest aphids, whitefly, scale insects and mealybugs. An extremely hungry ladybird can consume 50 aphids per day. To ensure that ladybird larvae have access to plenty of aphid prey, their eggs are laid among a young aphid colony.
“You can tell a ladybird’s age by the number of spots” Spots actually indicate species. (Two-spotted ladybird, 10-spotted ladybird..)
“Those big white spots are the ladybird’s eyes”. Those white spots are there to scare predators.
Majerus, M. E. (1994). Ladybirds. HarperCollins Academic.
Roy, H., Brown, P., Frost, R., & Poland, R. (2011). Ladybirds (Coccinellidae) of Britain and Ireland. Natural Environment Research Council (NERC).
Featured image from www.alexanderwild.com.