Butterflies bring more than just beauty to our gardens – they play a crucial role in maintaining healthy ecosystems. From pollination to serving as a vital food source, these enchanting insects are essential for the delicate balance of nature.
While butterflies are universally cherished, the sight of nondescript caterpillars often triggers panic and a desire to eliminate them from our precious plants. However, we tend to forget that these seemingly insignificant caterpillars will soon undergo a magnificent transformation into stunning butterflies. Moreover, their role in the ecosystem is immense.
Caterpillars and Birds: The absence of caterpillars would lead to a decrease in bird populations and the collapse of numerous food chains. For instance, consider the Blue Tits while feeding its chicks. Throughout the day, these birds embark on over 600 trips back to their nest, each time carrying a vital food source – caterpillars! These caterpillars form the basis of their diet, and their absence would affect not only the Blue Tits but also other small birds that rely on them for food.
Caterpillars and Trees: A common belief is that caterpillars damage trees and harm vegetable and ornamental plants. However, a closer look reveals a different story. One of the purposes of plants is to serve as food in the food chain, and they are designed to produce more leaves than they need. This abundance of leaves provides sustenance for animals that exclusively feed on plants.
Please take a look at the forest ecosystem as an example. Many caterpillars inhabit the forest, often mislabeled as pests. Surprisingly, the minor damage caused by caterpillars can stimulate plant growth and increase productivity. The loss of part of the vegetative mass is a natural part of the plant’s development program. It is all part of a wise mechanism of ecological balance.
When caterpillars are considered pests and pesticides are used to eliminate them, the leaves in forests remain intact. However, this creates a problem: the leaves accumulate and don’t decompose properly. As a result, oxygen and water struggle to reach the tree roots, leading to a gradual decline in tree health.
On the other hand, in forests where caterpillars are allowed to thrive, they consume more leaves. This ensures a healthier amount of leaves in autumn. This leaf mass has decomposed by spring, enriching the soil with organic matter. Moreover, the caterpillars’ excrement, totaling over 200 kg per hectare of forest, acts as a natural fertilizer. This delicate balance ensures the vitality of the ecosystem. (Zhdanova, 2010)
During periods of mass caterpillar reproduction, oak trees may lose their leaves by the end of May. However, the trees do not perish but rather sprout new foliage. Though their annual wood growth is reduced, the younger plants in the shade of mighty oak trees receive more light and begin to flourish. Furthermore, the soil beneath the trees benefits from the abundant insect excrement, nourishing the trees and surrounding vegetation.
Nature is far more complex and intriguing than our simplified notions of good or bad, useful or harmful. Every species, even those labeled as pests, has a crucial role to play in the intricate cycle of matter and the preservation of ecological balance.
Caterpillars and Crops: The presence of the cabbage white butterfly often raises concerns among gardeners, considering it a common nuisance. However, let’s look beyond its impact on cabbage alone and discover its vital role in the ecosystem.
Centuries before humans started cultivating cabbage, the Large and Small White butterflies coexisted peacefully with various cruciferous plants. These beautiful butterflies would lay their eggs on a diverse range of plants, including Armoracia rusticana, Berteroa incana, Brassica campestris, Brassica rapa, Capsella bursa-pastoris, Isatis tinctoria, and others. Interestingly, many of these plants are often labeled as weeds due to their aggressive growth, out-competing other species in their surroundings.
Here’s where the Large and Small White caterpillars come into play. They serve as natural regulators, controlling the expansion of these cruciferous plants and maintaining balance within the ecosystem. However, as humans actively combat these so-called weeds in gardens, parks, and roadsides, the butterfly’s options for laying eggs are limited, leading them to target cabbage plants instead.
I want to remind you that only 2% of caterpillars feed on vegetable crops and fruit trees. The remaining 98% feed on weeds and help control their spread, just like in the example with the cabbage butterfly. Each butterfly species has specific host plants on which its caterpillars will feed after hatching from eggs. For instance, the scientific name of the Small Tortoiseshell butterfly, Aglais urticae, refers to its close association with nettles (Urtica dioica). Nettles serve as the primary food source for the caterpillars of this butterfly species.
So, if you see a cluster of black caterpillars on nettles, don’t rush to destroy the bush or shake the insects into your neighbor’s yard. Just kidding! Despite being voracious eaters, even many hungry Small Tortoiseshell caterpillars won’t eat nearby vegetable or berry crops. At most, they’ll enjoy munching on hops leaves.
The Swallowtail butterfly (Papilio machaon) is another well-known species whose caterpillars have a particular diet. They exclusively feed on plants from the Apiaceae family. This family includes plants commonly known as the carrot family, such as parsley, dill, fennel, and Queen Anne’s lace. But also, the Apiaceae family includes a significant number of phototoxic species, such as giant hogweed, and a smaller number of highly poisonous species, such as poison hemlock, water hemlock, spotted cowbane, fool’s parsley, and various species of water dropwort. The Swallowtail caterpillars play a big part in controlling these plant populations, which helps maintain a balanced ecosystem.
So, the next time you spot caterpillars in your garden, don’t panic. Please take the opportunity to identify these caterpillars and learn more about them.
Caterpillars don’t crawl through the garden in search of food. If you spot a confident caterpillar along a garden path or lawn, it’s probably looking for a cozy place to pupate. The instinct of self-preservation drives them to undertake long journeys to find a safe spot underground, in a pile of leaves, on a fence, or inside a garden building.
If a caterpillar can escape from birds and gardeners with bug sprayers, a beautiful butterfly will grace your garden in no time.
In the upcoming blog posts, we will explore ways to protect your crops without using insecticides. By gaining a deeper understanding of the broader ecological picture, we can truly grasp the importance of these incredible insects beyond their effects on our harvest. So, stay tuned as we explore harmonious solutions that allow us to coexist with the diverse and captivating world of butterflies and, most importantly, caterpillars in our gardens.
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