Ladybugs, also known as ladybirds, lady beetles, lady cows, and, scientifically, as Coccinelidae, are a family of small beetles. The name of ‘Coccinelidae’ may derive from Latin, where the word ‘coccineus’ means ‘scarlet’, or it may derive from Latinized Greek, where the word ‘Kokkos’ makes reference to a seed or a berry of a rounded, convex shape, thus alluding to the shape of the ladybugs themselves.
Coccinelidae is the biggest family of the superfamily Cucujoidea. Not surprisingly, thus, there are around 5,000 – 6,000 different species of ladybugs across the world (with more than 100 existing in Europe and more than 450 native to North America), classified into 370 genera. It is possible, though, that the number is in reality much higher, seeing as a lot of ladybugs are not yet described, given a name, or assigned to a particular category. The most common species around the western world are:
The two-spot ladybugs (Adalia bipunctata)
- they are usually 4 — 6mm in length;
- they have a red wing case, with a single black spot on each side;
- overall, the coloration and the patterning can vary.
The seven-spotted ladybug (Coccinella septempunctata)
- they are usually 5 — 8mm in length;
- they have a red wing case, with three and a half spots on each side.
Description and distribution of ladybugs
Ladybugs appear as dome-shaped, either round or oval, depending on the species. They are small, ranging from 0,8mm to 18mm long, with black heads (which have white patches on each side), 6 short, black legs and antennae. The colourful backs are actually wing cases, which act as protectors of the delicate wings that are folded up beneath them. Generally, they are yellow, orange, or scarlet, with tiny black dots on their wing covers, but the reality is that the colouring varies greatly according to species. Vibida duodecimguttata, for example, is a species of ladybird that sports white dots on a reddish-brown background; some ladybugs are mostly or entirely black, dark grey, grey, or brown, and some may even have stripes or no distinctive markings at all. Needless to say, this makes it very difficult for researchers to correctly identify and categorize them. The attractive colours and these distinctive spots are meant to decrease the appeal that they may have to different predators, a phenomenon called aposematism.
Breeding and dietary information
Ladybugs are holometabolous insects, which means that they undergo a complete metamorphosis into adulthood. A typical ladybug’s life is composed out of 4 main stages: egg, larva, pupa, and adult.
Although the exact number varies greatly and depends on species and environmental conditions (such as climate, availability of food, etc.), ladybugs can lay hundreds of eggs, in batches of various sizes, which are usually strategically placed on leaf surfaces close to the colonies of aphids that are the species’ primary prey; these are around 0,2-2mm long, oval or spindle-shaped, with a colouring ranging from white, to yellow, to red. This stage usually lasts between 2-18 days, depending on the environmental conditions. Larvae begin feeding immediately once they have hatched, often on unhatched eggs, be them fertile or infertile. The newly hatched larvae have about one to one and a half days to locate their first prey; if they are unsuccessful, they soon die. Some species of ladybugs are thought to lay infertile eggs next to fertile eggs, apparently so as to provide a backup source of food (and, possibly, to increase the chances of survival of other larvae), with the ratio of infertile to fertile eggs thought to increase as the availability of food at the time of laying decreases.
Depending on this availability of resources, larvae pass through 4 instars over a period of 10-14 days, separated from each other by a moulting period. Pupation follows, and, after another short period of several days, reproductively active adults emerge. Only adults are mobile in the real sense of the word, able to cover vast distances, using their wings, in search for food and mating partners. They mate within a few days following emergence, usually in the spring, with females laying eggs during late spring and early summer. Where the first 3 stages (egg, larva, pupa) can be measured in mere days, once adulthood is reached, the unit of measurement changes to months, with a ladybug’s total average lifespan being of 1-2 years. There are, however, species that can only live up to a couple of months.
Ladybugs that inhabit temperate regions enter diapause during the winter; this is basically a survival mechanism that involves a delay in development. As a result, ladybugs are often among the first insects to appear in the spring. Some species (such as Hippodamia convergens, colloquially known as the convergent lady beetle) tend to gather in groups and move to higher elevations, such as mountains, in order to enter diapause. Regardless of the manner in which they overwinter, most ladybugs do so as adults, aggregating on the south sides of large objects such as trees, houses, etc., snuggling up in dense vegetation, under logs, and sometimes even inside homes (in door and window frames, folds in the curtains, etc.), sheds and outhouses, and dispersing as the days become longer with the approach of spring.
When it comes to feeding habits, ladybugs can be classified into 2 main groups: predaceous and phytophagous.
Predaceous ladybugs are predators, feeding mainly on Sternorrhyncha, a suborder of insects which contains aphids, whiteflies, and scale insects. However, there are also species in this category whose prey range is wider, such as the genus Stethorus, which contains black ladybugs that feed on spider mites (Tetranychus). Some ladybugs even prey on caterpillars, various beetle larvae, eggs and larvae of moths, etc. Aside from this carnivorous diet, ladybugs also consume honeydew, pollen, plant sap, nectar, and various fungi and plant tissue. Although the importance of such non-prey items in their diets in still largely not agreed on, it is known that they not only supplement the diets of ladybugs, but also represent important food sources when the usual prey is scarce or difficult to find; on their own, they are generally sufficiently nutritious for an adult ladybug to survive, but not enough for a larva to develop.
Phytophagous ladybugs are herbivorous; all species of Epilachnini can be classified as such, feeding on various plants belonging to Cucurbitaceae, Solanaceae, Fabaceae, Convulvulaceae, Malvaceae, etc.
Interestingly, the female ladybug eats much more than the male. Generally, an adult is capable of consuming as many as 270 aphids a day, while a single larva can consume between 600 and 1,200 aphids during its development.
Ladybugs as pests
Many people are fond of ladybugs because of the colourful, spotted appearance that they have; this is especially true of children, to whom they are an object of interest and, most often than not, a favourite insect. Funnily enough, because of their colouring, ladybugs are sometimes referred to as the “Halloween Ladybug.” Many cultures actually consider ladybugs to be lucky; the Turkish name for the insect can literally be translated into “good luck bug”, and spotting a ladybug, in Turkey as well as in other countries, such as Russia and Italy, is considered to be either a call to make a wish or a sign that a wish will soon be granted. In many other parts of the world, superstition states that it is unlucky to kill a ladybug.
Ladybugs are generally also considered to be beneficial to gardens, orchards, agricultural fields, and a variety of similar places, seeing as, as previously mentioned, they consume plant-eating pests, thus helping protect various species of plants and crops. Although most ladybugs are generalist, in the sense that they consume a wide variety of pests, some favour certain prey types, which causes them to be particularly valuable as agents in biological control programs.
However, there are a couple of species of ladybugs that do not eat plant-eaters, but plants themselves. The Mexican bean beetle and the squash beetle, to name just two, are among the most destructive ladybugs, preying aggressively upon the crops that are named after. Although, in the long run, they only cause mild overall damage, in the years that they have few natural enemies, their numbers can increase explosively, and the damage they can do if not deal with correctly and immediately is major.
Ladybugs are also a problem when they enter homes in large numbers. This usually occurs in the autumn, as they begin to search for a warm place to spend the winter, with homes and buildings close to fields and woods being particularly vulnerable to infestation. Some species are also known to aggravate asthma and cause allergic reactions in some people, a strong reason for ladybug pest control. In addition, they exude a viscous yellow, foul-smelling defensive fluid that may stain whatever it contacts.
Getting rid of them can be done through several methods, depending on where an infestation occurs. Outside, the main predators of ladybugs are birds, although wasps, dragonflies, spiders, and frogs also prefer them. In defending themselves from these predators, ladybugs secrete a fluid, an alkaloid toxin, from the joints in the exoskeleton – a phenomenon referred to as reflex bleeding – which gives them an unpleasant, bitter taste and which leaves a yellow, foul-smelling stain on the skin; this is triggered by mechanical stimulation in both larval and adult ladybugs. This, combined with the bright, distinctive colouring, can be very effective as far as predators learning to avoid them is concerned. When threatened, they may also try to play dead, taking advantage of the fact that many predators will not eat an insect that is not moving.
If you are having trouble with ladybugs inside of your home, the treatment options are limited. The easiest way to remove ladybugs, once they are indoors, is with a vacuum cleaner, and then, for the remaining few, you can use aerosol insecticides, if necessary. The best way of preventing them from entering your house is by sealing ladybugs out by caulking cracks and around utility service openings, fixing broken window screens and door jams, plugging cracks in the foundation or roof. For more details on how to ‘Prevent infestation with Ladybugs’ or ‘How to get rid of Ladybugs’, visit our related articles, and you will find more methods of prevention or exclusion, that you can apply against these pests.