by Dr. Swati Saxena
Visiting Scientist, Department of Biology, University of Toronto
Photos by Dr. Saxena and her lab colleagues unless otherwise noted
Ladybirds, also known as lady beetles or ladybugs, are one of the lovable and familiar insects belonging to the family Coccinellidae. The majority of ladybird beetles feed on crop pests and function as biocontrol agents, reducing populations of insects that damage crops and gardens.
Though many types of beetles are found in our gardens, ladybirds are recognisable by their round or oval shape bodies. Ranging from one to ten mm in size, they have different beautifully coloured patterns on their hardened forewings (called elytra). These patterns can be in the form of either/both dots and lines.
By planting brightly coloured flowering plants or the leguminous plants such as peas, beans, climbers, you can easily welcome ladybirds to your garden during the spring and summer when the temperature is around 25℃.
Now a quick question for the readers: Have you ever thought why these beetles are called ladybirds?
The term ladybird refers to the Virgin Mary because of the resemblance of scarlet elytral (wing) colour with Her Cloak. Ladybirds not only benefit our gardens but they also have aesthetic importance. Various products we use are designed with the ladybird shape and they have always been associated with good luck charms. Below are a few images which show that ladybirds bring joy to our day to day lives.
Photos by Tosyum https://www.flickr.com/photos/tosyum/
As a researcher, I always read scientific articles on ladybirds, but never thought that ladybirds could be the subject of a nursery rhyme, too, until I was in a bookstore and came across a poster with a poem printed on it:
“Ladybird, ladybird fly away home,
Your house is on fire and your children are gone,
All except one,
And her name is Ann,
And she hid under the baking pan.”
This incident made me search for more ladybird poems. It was interesting to find that ladybirds are quite attractive to children across the world in the form of nursery rhymes and bedtime stories.
Ladybirds are an ancient and successful group of insects which undergo metamorphosis, a complete life cycle starting from the egg which gives rise to larva and passes through four larval stages or instars. The final larval stage forms the pupa which finally changes into an adult.
The food of ladybirds includes aphids (which are most commonly found in our gardens) and other small insects, but not all ladybirds feed on small insects. Some feed on fungi, pollen, honey dew, and mildew that forms on the plants and pollen. However, the larvae are strictly carnivorous.
Above, seven-spotted ladybird (Coccinella septempunctata), prevalent in Ontario but native to Europe, eating oleander aphids (Aphis nerii) on common milkweed.
Like other organisms in nature, ladybirds are also impacted by seasonal changes and temperature. It is often observed that during winter season when temperature drops severely, ladybirds start aggregating in residential backyards such as below logs, and sometimes inside the house.
Above, harlequin ladybird (Harmonia axyridis) native to eastern Asia.
The change in the temperature not only limits the activity and growth of ladybirds but also changes the pattern and colour of their wings.
Below, zig-zag beetles (Cheilomenes sexmaculata), native to India (two morphs of same species).
At low temperatures At high temperatures
Organic farming has recently been regaining popularity and biocontrol agents play an important role in this. There are several biocontrol agents such as mites, wasps, and mirid bugs. Ladybirds are well known and widely used as the biocontrol agents. Several stories exist regarding the success of ladybirds as biocontrol agents. For example, their use in biocontrol came into existence when the vedalia beetle (a type of ladybird), was selected to control the population of scale insect on citrus in California (USA) in 1889. A need for aphid biocontrol led to the introduction of 179 ladybird species in North America since 1900, but only 18 have successfully established. Although in Canada, few farmers have started using them as the source to control the pest population, biocontrol of insect pests has a promising future as it is the eco-friendly and cost effective way of pest management. Ladybirds play an important role in this!
Our native convergent ladybird beetles live in a wide variety of habitats, but in certain areas, they are being outcompeted and replaced by the invasive Asian Ladybeetle. There is an utmost need to understand the importance of ladybird wellbeing at all levels of influence.
What can you do to protect and support ladybirds? Providing natural habitats and considering your garden as an ecological community is a solution.
Recent studies show that ladybirds also act as the major bioindicators by responding to the environmental changes. Since we are living in the core of urbanization, it is the time to spread awareness within our communities about these insects by sharing with them the proper knowledge of ladybirds and their importance in ecology. Since all beetles are not beneficial, it is necessary that people should recognize and encourage the beneficial ones and act accordingly.
Resources
Identification of Ladybird beetles https://bugguide.net/node/view/179
Ladybird beetle conservation: