One of the most common butterflies that can be seen in many parts of the world is the Cabbage White butterfly. The scientific name for this species is Pieris rapae, it belongs to the Pieridae family, and these butterflies may be called “whites and yellows” due to their coloration.
The Cabbage White moniker comes from their favored plants to eat which are cabbages and certain other brassicas. A female Large White butterfly lays eggs on the undersides of the leaves in groups of 40-100. In comparison, the Small White female will only lay a single egg under each cabbage leaf.
But, in both cases, the larvae will emerge from the eggs in 1-2 weeks and voraciously eat the leaves. The Small Whites will tend to eat into the heart of the cabbage which makes them a threat to crops even in smaller numbers.
Cabbage White Butterfly Anatomy and Identification:
The best way to identify a Cabbage White butterfly accurately is to carefully examine its physical characteristics and behavioral patterns. A Cabbage White has white or pale-yellow wing coloration with stark black markings which vary from male to female.
Males often have a black spot located near the forewing tip and females have 1-2 extra spots on their body and upper wings. The wingspan varies from 1.6 inches (4 cm) up to 2-4 inches (6 cm). But the size or shape of the wingspan is not an accurate identifier between males and females.
Lifecycle and Behavior Cabbage White butterfly:
The Cabbage White butterfly has four distinct stages of life: egg, larva (caterpillar), pupa (chrysalis,) and finally the emerging adult butterfly. This process is fairly similar throughout butterfly species, let’s take a look at the metamorphosis in more detail:
The Egg: The female will lay a single egg (Small White) or 40-100 eggs (Large White) on the underside of cabbage family (cruciferous) plants. The eggs are tiny, they have a cylindrical shape, and they are pale yellow. The eggs hatch within 1-2 weeks and tiny caterpillars will emerge and begin to eat.- The Caterpillar: The caterpillars have segmented green bodies with several prolegs and three pairs of real legs that do all the work. During its growth, the caterpillar will undergo multiple molting stages (instars) where the exoskeleton is shed, and the larger caterpillar emerges. To support this rapid growth over the first few weeks of life the caterpillar will eat the host plant leaves causing damage.
- The Chrysalis: When the caterpillar has reached its full size it’s ready for the chrysalis stage. The caterpillar will attach itself to a surface with spun silk threads and form a hard shell to cover its body. After a short time, the chrysalis will transform into a yellow or pale green color with a small oblong shape. Within the chrysalis, the caterpillar will undergo a 7-10 day metamorphosis process to transform into the adult butterfly.
- Adult Butterfly: The adult butterfly struggles free from the cocoon, but it cannot fly until its soft and crumpled wings are dried and stiffened which takes a few hours. An adult Cabbage White butterfly has pale yellow wings, and you may see the black spots to identify males and females of the species. When the butterfly is ready to fly, it will take to the air to search for nectar to eat and a mate to continue this lifecycle.
This entire process from a laid egg to the emergence of the adult butterfly typically takes several weeks to complete. There are variations due to food availability, temperatures, and other factors.
Cabbage Butterfly Interaction with Gardens:
Cabbage White butterflies are excellent plant pollinators because they feed on nectar and a coating of pollen is transferred to the next plant they visit. For this reason, you want plenty of butterflies, bees, birds, and other pollinators in your garden. But, there is a price to pay when the butterflies are young, they truly are the most voracious eaters of plant matter. They can cause a lot of damage to plants and crops in next to no time in three key ways:
- Leaf Feeding Damage: The Cabbage White caterpillars will feed on cruciferous plants, such as cabbage, cauliflower, kale, broccoli, mustard greens and others. The consumption of large quantities of plant matter will inevitably lead to defoliation.
- The Extent of the Damage: When a caterpillar feeds on a leaf, it chews at the edges and creates an irregular hole. This removes patches of tissue from the leaf surface which causes a degradation of plant vigor and a reduction in crop yields.
- The Loss of Crops: If a significant area in a garden is set aside for food production or commercial crops fall prey to large numbers of caterpillars this is a problem. When plants lose their leaves their ability to photosynthesize is compromised. The plant is less able to produce the energy it needs to drive growth and food production.
There are some ways to manage Cabbage White and other butterflies which we will cover below.
Ecological Importance:
When you consider the potential extent of the damage that can be caused by Cabbage White caterpillars, it may seem strange to talk about their ecological importance in the very next paragraph. But, all butterflies have an important role to play that may vary depending on their interactions and the specific ecosystem they inhabit.
Let’s look at the two main reasons why these butterflies are vital for your local ecosystem:
1. Pollination
As we briefly mentioned earlier, an adult Cabbage White butterfly feeds on nectar found in flowering plants where they pick up pollen. This pollen is then transferred to another flower when they feed again to encourage plant reproduction. Although butterflies are not as efficient as bees as pollinators, they do support the diversity of an ecosystem.
2. Acting as a Food Source
A Cabbage White has a number of predators, including birds, ladybugs, parasitoid wasps, spiders, and more. They may feed on them in caterpillar form or hunt them as adult butterflies. Butterflies are an abundant source of protein for these predators which naturally regulate the local insect populations. As a food source, the Cabbage White and other butterflies can still contribute to the balance of an ecosystem.
A Cabbage White butterfly in its native region is a vital part of the ecosystem. But, in areas where the butterfly has been introduced, they require significant management to offset the potential negative consequences.
Large populations of recently introduced Cabbage White butterflies could negatively affect the interactions between plants and their pollinators. They may even outperform the native butterfly species, which could lead to a decline in numbers. If the butterflies are invasive, they may even cause significant damage to the local plant life which can be difficult to repair.
Managing Cabbage White Butterflies:
It is possible to manage Cabbage White butterflies effectively with a few simple strategies.
First, use crop rotation and remove any plant debris that remains after harvesting to reduce the risk of pupae overwintering in your garden.
Next, add some row covers or netting which will act as a physical barrier to prevent female butterflies from laying eggs on leaves.
Finally, you can use biological or chemical control methods to keep the population of butterflies in check. A natural biological solution could be adding predatory beetles, ladybugs, parasitic wasps, or other natural predators.
A chemical control method should be the last resort to deal with a severe infestation. Using chemicals can have wide reaching ramifications for the entire ecosystem.
Conclusion:
A Cabbage White butterfly is a beautiful and fascinating inhabitant or visitor to your garden. These and other butterflies have an important role to play in the ecosystem and they can encourage prolific plant growth.
But, there are risks, if there are too many caterpillars the plants can be damaged which may lower crop yields. So, some management may be required to keep the butterfly population in check if they become invasive.