Interaction of Butterflies & Moths with Host Plants

Lime butterfly gets its name from host plants which are usually citrus species (such as lime). Shot at the Poomaale Estate, Coorg. 

Several organisms have built a close relationship with each other over millions of years of evolution. Animals depend on each other for food, creatures camouflage with their environment to ward off threats, flowers and leaves indicate the changing season (and the environment’s health)..and the list goes on! 

Among these many everyday interactions between the elements of nature, one of the most common and eye-pleasing ones is that of butterflies and flowering plants. We have all made colourful drawings of it during childhood and tried to capture the beautiful fluttering moments as we grew up. But in this charming frame, there is an unseen give-and-take of ecological favours – those that are responsible for the very existence and continuity of the subjects of the frame.

Hold on though, as we have another member in the frame. The humble moth, generally perceived to be not as attractive as the butterfly, plays its role exceptionally well in this ecosystem of codependence.

Butterflies & Moths – How Similar or Different Are They?

Both butterflies and moths belong to the order Lepidoptera due to the presence of minuscule scales on their wings. Even though it is the butterflies that are more popular among humans, the moths seem to be more popular in the rest of the natural world. Their population is much higher than that of butterflies. Among the species of the Lepidoptera order, moths make up about 90% of them and butterflies merely 10%. Another major similarity between the two is their metamorphosis – the complete change of form from eggs to caterpillars, to cocoon/chrysalis and finally the winged adult. One can easily mistake a moth caterpillar for a butterfly caterpillar and vice versa.

Despite being fundamentally similar – both in terms of looks and lifecycles, they do possess many differences which have led to distinct categorisation. 

The most visible one is their wings. Butterflies fold their wings behind their body while sitting, while moths spread their wings flat and wide. The presence of ‘frenulums’ in moths (wing-coupling element in the body) allows them to display their wings as a unified canvas. Another differentiating feature is the shape of the antennae – saw-shaped in moths and hammer-shaped in butterflies. The metamorphosis is largely the same, except for the cocoons. Moth cocoons are silky soft (often exploited – like the Bombyx mori – to produce silk) whereas butterfly cocoons are hard (called chrysalis and not cocoons).

Activity time is also a major distinction. Butterflies are generally active during the day and moths are active at night. Exceptions exist in all rules and the case of butterflies and moths is no different. There are moths that look surprisingly like butterflies (like Castnioidea from Indonesia and Australia) and there are butterflies that are active during dawn and dusk. It only goes to indicate the extent of complexities that exist in evolutionary beings.

How Do Host Plants Benefit Butterflies & Moths?

The nectar of flowers, and sometimes the juice of rotting fruits, is the main source of food for butterflies. While many moths do depend on nectar greatly, their taste has evolved to be a bit more diverse. Some moths feed on plant leaves, rotting wood/fruits and even on fabric (like the common clothes moths).

Besides food, plants provide shelter to the eggs, caterpillars and cocoons/chrysalis of butterflies and moths. Once the eggs hatch, the caterpillars munch on the plants for nourishment and shelter them once again as they transform into cocoons. Once the butterflies and moths emerge from their self-crafted shells, the cycle repeats and continues. This way plants not just provide them with food, but support the entire life cycle of these fluttering species. 

How Do Butterflies & Moths Return the Favour?

Pollination – the process through which flowering/fruiting plants reproduce and evolve – is steered steeply by butterflies and moths (including other insects like bees and flies). Though plants pollinate through wind too, pollination by insects is more reliable and precise. Pollination by wind is random and can be limited to a region, but insect pollination is purposeful and wide-ranging improving biodiversity and helping the species evolve.

What Kinds of Plants Host Butterflies & Moths?

Bright, colourful and strong-scented flowers attract butterflies and moths. The leaves that caterpillars feed on are also a deciding factor. For example, the lo moth favours cherries, willows and raspberries. Caterpillar-friendly plants, both in terms of food and shelter are preferred. Leaf litter provides additional shelter to them. Overly clear grounds may not bring butterflies or moths to your gardens and farms. 

The mutualistic relationship between plants and butterflies has evolved to an extent that certain species cannot survive without their butterfly/moth counterparts (like the Yucca plant and yucca moth; monarch butterflies and milkweeds). The shapes of some flowers are evolved in a way that allows only specific butterflies to access the nectar and help them pollinate. This exclusive mutualism is an indicator of the closeness plants show towards butterflies and moths. While it applies to a select few species, growing native plants is a thumb rule when attracting butterflies or moths. Keeping the environment free of chemical fertilizers is also important as soil health greatly affects the nectar quality, which results in repelling butterflies and moths.

Moths Like to Stand Out

Diverse is what moths look for – diversity of food, habitats, activity and their very being. Not all species of moths help as pollinators, but they do have a mutualistic relationship with plants and sometimes become a source of food for birds. They do not exclusively lay eggs on flowering plants. Grasses, shrubs and vines are equally welcoming to them. Many moth caterpillars feed on weeds as well! Having the right variety of vegetation in your gardens and farms makes a comfortable habitat for both butterflies and moths.

The mantra to attract butterflies and moths is by not trying too hard! You can get some weeds to grow (but not take over the garden), plant diverse plants (preferably those that bloom in different seasons) and not overclean! Let some leaves and debris fall as they provide a safe ground for moths and butterflies to hide from predators. Using chemical pesticides can repel them. So you can introduce nature pest control plants like Citronella and Calotropis can help you manage your gardens and farms without harming the environment. Applying some eco-logic and making small adjustments to your processes can give you results beyond your imagination. A little learning (and unlearning) and understanding the way of nature are all we need to live in harmony with its wonderful creatures, enjoying the hidden advantages they bring along.