Ladybugs, Coccinellidae, are a vast family of insects belonging to the order Coleoptera. Today, we want to dedicate a special in-depth analysis to this adorable insect, as it is one of the most beneficial creatures in our organic garden. Fortunately, in nature, there are not only parasitic insects that damage crops but also useful insects. Among them, ladybugs deserve special mention. These small beetles play a vital role in defending our plants from troublesome insects throughout their normal biological cycle.
In this article, we have decided to get to know them better. We will explore their life cycle and observe the various species found in our area, distinguishing them by their “preferred parasite”. Another essential topic we will examine is how to welcome them best in our organic garden, trying to promote their proliferation as much as possible. This involves providing winter protection using special “useful insect houses”. Of course, we must emphasize that only those who practice organic and sustainable agriculture can look with interest at ladybugs. The use of chemical pesticides destroys the entire ecosystem, and those who use them cannot expect the help of beneficial insects.
Characteristics of Ladybugs
Ladybugs are widespread insects found all over the world, with over 6,000 different species. In English, they are called “ladybugs”, perhaps due to their gentle appearance. Their presence is often associated with the idea of an organic garden.
As adults, these small beetles have the characteristic spherical shape that we all know. They have a semi-spherical form and vary in size from 2 to 7 millimeters in length, with some rare species reaching up to one centimeter.
The upper part of their body is composed of elytra, which are true wings that ladybugs spread to move from one plant to another and undertake long migrations.
The elytra are smooth, brightly colored (red, yellow, black), and feature distinctive spots. These spots, in terms of number and shape, identify the species, and entomologists use them to classify the insect.
The bright colors and spots on their exoskeleton serve to deter predators. Additionally, ladybugs have a highly unpleasant-smelling liquid that they secrete from the joints of their tiny legs (three pairs) when they feel threatened, defending themselves from predators.
Life Cycle of Ladybugs
The life cycle of ladybugs begins with oviposition, where they lay their eggs directly on plant leaves, near the prey the ladybugs will feed on.
The eggs are yellow or light orange and can be numerous due to the female’s high fertility. Some species can produce up to 2,000 eggs.
After hatching from the eggs, the ladybug larvae go through a three-week-long larval stage. They have an elongated shape and are equipped with setae on their upper body. Generally, they are dark-colored.
At the beginning of this stage, they are not very mobile, but they gradually become more familiar with their surroundings and start moving in search of food. Even at this stage, they begin to feed on parasitic insects.
The larva of a ladybug, when it reaches maturity, transforms into a pupa. During this phase, its size is about 4-6 mm. Normally, it remains attached to the plant where it has grown.
After approximately one week, the pupa hatches, and the adult insect, our beloved ladybug, emerges. It immediately starts preying on parasitic insects.
The entire development cycle lasts about a month or slightly longer.
Depending on the species and the ecosystem in which the ladybug is settled, there can be 1 to 6 generations in a year.
Under suitable conditions, they live for about a year, although some species can live up to 2 years. These beneficial insects exhibit some distinctive behaviors, such as gathering in a colony of ladybugs and migrating in groups to areas with more favorable climatic conditions.
The usefulness of ladybugs for organic garden defense
As we have mentioned several times, ladybugs are exceptional predators. They feed on numerous parasitic insects in crops, and what distinguishes them is their extreme specialization. There are species that mainly feed on aphids, others feed on scale insects, some on mites, and even some that consume fungi responsible for cryptogamic diseases like powdery mildew and downy mildew.
For this reason, ladybugs are essential beneficial insects for biological pest control. Therefore, we must strive to protect and preserve them by avoiding the use of chemical pesticides.
How to attract ladybugs to the garden
If we want to facilitate the presence of ladybugs in our organic garden, especially in winter, we can use some measures.
These beneficial insects will seek a suitable place to hibernate in autumn, and then resume their activity in spring.
They usually seek refuge in crevices in tree bark, under dry leaves, beneath stones, or in sheltered places.
Pay attention to the presence of ladybugs in pruned branches or mulch. These materials are usually discarded, but they are essential for the survival of the insect.
In any case, if you want to be welcoming to these little beetles, you can use insect houses.
Insect houses are wooden structures of varying sizes that resemble small cottages, and ladybugs can find refuge in the dedicated gaps to shelter from the cold.
If you are passionate about do-it-yourself projects, you can craft a small insect house using pieces of wood and recycled materials, such as old perforated bricks. Alternatively, you can purchase them online from various vendors by clicking on this link. There is a wide variety of choices, as you can see, and the designs are cheerful, adding a touch of color to the winter organic garden.
Regardless of your choice, whether you opt for a DIY insect house or purchase one online, it’s essential to securely fix the structure to the ground with wooden stakes, preferably near the garden and in a sunny location.
Ladybugs are beneficial insects naturally present in nature. However, due to their significant role, they are bred and commercially available from so-called bio-factories. These facilities offer ladybugs for purchase (also online) at reasonable prices to populate and defend organic gardens.
Buying insects online is a common practice, and the insects for sale are usually delivered in special containers. These containers can be placed near the plants to be protected, but a more direct method is to distribute the insects directly onto the foliage of plants besieged by pests.
Now, let’s see which species are most interesting for defending the organic garden.
Ladybugs for Fighting Aphids
The first species we present is probably the most well-known. It is the Septempunctat, also known as the seven-spot ladybug or common ladybug.
The adult ladybug reaches a size of 6-7 mm and is characterized by reddish-orange elytra marked with 7 black spots, 3 on each elytron and one in the center.
This ladybug is a formidable predator of aphids in herbaceous crops and usually completes one generation per year. It is highly active during the spring season. It primarily follows the presence of aphids on plants and can consume up to 100 aphids in a day!
In autumn, it enters a resting phase and hibernates, finding a suitable refuge.
The Adalia Bipunctata
Another famous ladybug useful for aphid control is the species Adalia Bipunctata, also known as the two-spot ladybug.
This species comes in different colorations, ranging from the more common one with red elytra and two black spots to those with black elytra and two red spots, or even with a uniform reddish or dark color without any markings.
The two-spot ladybug can complete two generations per year. It is one of the most bred and commercialized species in bio-factories due to its resistance and voracity.
Ladybugs for Fighting Scale Insects
The two most widespread ladybug species used to fight scale insects are:
The Chilochorus Bipustulatus
The ladybug Chilochorus Bipustulatus is characterized by a very dark appearance. Its spots are reddish-orange, close together, almost forming a band rather than individual spots.
It can develop three generations per year and is the natural predator of the peach silver scale and San Jose scale.
The Cryptolaemus Montrouzieri
The second species used against scale insect attacks is the Cryptolaemus Montrouzieri.
It lacks spots and has a waxy appearance. It is very active in southern regions, preferring a warm climate and It can complete up to six generations per year and is an avid predator of the citrus mealybug.
Ladybugs for Fighting Mites
The Stethorus Punctillum
For mite control, the most relevant ladybug species is the Stethorus Punctillum. The adult ladybug does not reach large dimensions, reaching a maximum size of 1.5 mm. It does not have spots but has a black appearance covered with microscopic hairs. It can complete two to four generations per year and is used for controlling the two-spotted spider mite in greenhouses and vineyards.
Due to its significance as a predator of mites, this species is among the most bred and commercialized.
The Ladybug for Controlling Fungal Diseases
The Thea 22-Punctata
Unfortunately, not only are “beneficial” ladybugs populating our organic gardens. In recent years, the Asian ladybug, Harmonia axyridis, also known as the “harlequin ladybug”, has been introduced to our country. The introduction of this species has been a serious mistake and should make us reflect on the risks associated with such practices, i.e, introducing non-native insects into a new ecosystem. It is a ladybug of large size and particularly aggressive.
Entomologists describe it as cannibalistic because it feeds not only on parasitic insects but also on the more docile native ladybugs we have just learned about. Consequently, it easily outcompetes other species. Moreover, it also causes problems in wine production (the reason for its introduction was to defend vines from aphids) since the liquid it secretes for defense against parasites is particularly unpleasant and toxic, much more so than our beloved European ladybugs.
This situation prompts us to carefully evaluate the opportunity to introduce non-native species into our ecosystems. Examples (although accidental) are the Asian stink bug and the tomato leafminer.
Naturally, our discussion has been limited to the ladybug species most relevant to agriculture. However, in nature, there are approximately 5,000 species of these beneficial insects for our organic gardens! It would be difficult to describe them all.
Nevertheless, we hope to have been helpful and comprehensive in our discussion, and we wish you successful organic cultivation!
- Instituto Nacional de Pesquisas da Amazônia – “OCURRENCE OF COCCINELLIDS IN A SPONTANEOUS PLANT CONYZA CANADENSIS (L.)” – The study registers the occurrence and the influence of meteorological factors in the species of coccinelids, associated with the self-grown plant Conyza canadensis (L.).
- OSU Extension Service – “Will ladybugs ruin my garden?” – The article reassures that ladybugs do not eat plant material. They are beneficial as they eat aphids, a notorious pest that can devastate a garden.
- Texas A&M University – “Are Ladybugs Harmful?” – The article discusses the annual invasion of ladybugs into homes and structures across the southern U.S. due to colder temperatures. Ladybugs are beneficial insects to gardeners as they are effective predators against soft-bodied insect pests like aphids. However, they can be a nuisance when they invade homes, as they can stain fabrics and are smelly when they die. The article provides tips on how to remove ladybugs from homes and prevent future entry.