Ladybirds

"Ladybird, ladybird fly away home..." - the origin of this old rhyme is a little obscure,
but for the gardener and farmer it might be better worded "...fly into my home...",
because these useful insects can help keep garden plants and agricultural crops free
from greenfly and other pests . . . . . .

The Coccinellidae is perhaps the best-known family among our native beetles (Coleoptera), because it contains the brightly coloured ladybirds. There are nearly 100 species of ladybirds found in Europe and about 40 of these are resident in the British Isles.

The commonest species in most localities are the two-spot ladybird (Adalia bipunctata) and the larger seven-spot ladybird (Coccinella septempunctata), shown above. The largest of the native British species is the eyed ladybird (Anatis ocellata), shown opposite, found in conifer forests and plantations. The black spots on the back of this species each have a distinct yellow boarder or halo, giving the appearance of 'eyes'. Hence its common name of eyed ladybird.

These, and many other ladybirds, are voracious predators, feeding in both larval and adult stages on aphids (greenfly), coccids (scale insects), mealybugs, whitefly and, occasionally, on other insect pests of garden and crop plants. Indeed, some predatory ladybirds, such as species of Cryptolaemus and Delphastus, are mass-reared on a commercial scale for use as biological control agents against mealybug and whitefly infestations in greenhouses.

There are some non-predatory ladybirds, like the yellow and black 22-spot ladybird (Psyllobora vigintiduopunctata), pictured opposite, which eat the mildews and other microscopic fungi that grow on plant tissues and thus may help reduce the incidence of certain fungal diseases in plants.

Apart from these largely beneficial species, there are a few herbivorous ladybirds which feed exclusively on the leaves and shoots of plants. These all belong to a separate sub-family called Epilachninae and some members of this group found in Europe and North America can be very destructive to the foliage of potatoes, cucumbers and other crops.

The bright colouring of ladybirds - generally red or yellow with black spots - is thought to have a defensive function, by warning would be predators, like insectivorous birds, that the beetles are distasteful. When disturbed or handled most ladybirds discharge drops of a bitter, pungent fluid from leg joints and other parts of the body - a habit known as 'reflex-bleeding'. This fluid is usually yellow or amber-coloured and will stain unwary hands, tainting the skin with a long-lasting smell - so beware and don't touch!

Several ladybirds, including the common 2-spot ladybird, are remarkable for their wide range of colour patterning. The typical form of the 2-spot ladybird, shown in the picture at the top of this page and from which it derives its name, has red wing-cases with a pair of large black spots. But beetles of this same species often have several black spots or more elaborate black markings, and a fairly common form is black with four red spots. All very confusing when it comes to identification!

Perhaps even more confusing to the casual observer is the close superficial resemblance in general body shape and colour between some ladybirds and leaf beetles. Leaf beetles belong to a completely separate and unrelated family called Chrysomelidae. There is a quick guide to the differences between Coccinellidae (ladybirds) and Chrysomelidae (leaf beetles) at the bottom of this page - not too difficult on close examination!

Adult ladybirds hibernate through the winter in sheltered places amongst dense vegetation, leaf-litter, under tree bark etc., or inside buildings, outhouses and sheds. They often invade houses, nestling around doors and window frames, or in the folds of curtains. If you find these sleepy individuals, have a thought to their future value in controlling garden pests - it takes little time to coax them carefully into a jar and move them to a garden shed, hedge bottom or other sheltered place outside, where they can finish their winter sleep. Some ladybirds become strongly gregarious as winter approaches and huddle together in large clusters, sometimes consisting of several hundred individuals. The reason for this behaviour is unknown, but it certainly can provide a colourful display.

Larva of the seven-spot ladybird feeding on aphids

Hence, coupled with the activity of the adult beetles, which are probably even more voracious than their larvae, just a few of these insects around the garden are of considerable benefit in natural pest control. Other beneficial insects, ranked together with ladybirds, as important natural enemies of aphid pests and deserving all the protection we can give them, are the young stages of hover-flies and lacewings.

Get to know the adult and larval stages of these beneficial insects by looking on aphid-infested plants during the summer. Recognition is the first step towards their protection and conservation. If you have to use insecticides, remember to choose the more selective and/or less persistent products which minimise harm to beneficial insects.

The harlequin ladybird, an Asian species, was introduced into North America more than 20 years ago for biological control of aphids. Since then, it has spread to Europe and more recently (2004) to Britain. Populations in North America have increased at an alarming rate over the last ten year and there are reports of increasing numbers in parts of France, Belgium and Holland. For more information about this aggressively invasive species, its current distribution status in Britain and how you can help monitor its spread, go to the HARLEQUIN LADYBIRD SURVEY WEBSITE or the UK LADYBIRD SURVEY WEBSITE.

(1) Sixteen-spot Ladybird, Tytthaspis (= Micraspis) species (about 3 mm long)
(2) Leaf Beetle, Chrysomela (= Melasoma) species (6-8 mm long)

Ladybirds, e.g. as shown in (1) above, belong to the beetle family Coccinellidae; Leaf Beetles, e.g. as shown in (2) above, belong to the family Chrysomelidae. Members of these different families can bear a close superficial resemblance to one another (as illustrated by the two beetles above), but can be distinguished by the structure of the antennae and legs:

The majority of ladybirds (Coccinellidae) are carnivores (predators) and largely beneficial. On the other hand, all the leaf beetles (Chrysomelidae) are herbivores, feeding on the leaves, shoots or roots of plants of one kind or another, and many are serious agricultural and horticultural pests (the well known Colorado Beetle, which feeds on potatoes, is a member of this group).