Butterflies evoke images of warmth, sunshine, summer gardens, and flowery meadows teaming with life. However, there’s more to butterflies than just their aesthetic value. They pollinate plants, are an indicator of a healthy environment, and they provide a food source for other animals. Sadly, the twin forces of habitat loss and human-caused climate change are now threatening some of the butterfly species with extinction. A new study conducted by the University of Cambridge researchers has shared a new way that every one of us can help save these vital pollinators. That is, to make landscapes more diverse with areas that provide cooler, shady places.
Butterflying wings and temperature changes
Their study, which appeared in the Journal of Animal Ecology, show that paler and larger butterflies, including common brimstone (Gonepteryx rhamni) and the large white (Pieris brassicae), are best able to protect themselves against environmental temperature changes. This is because they can angle their reflective, large wings concerning the sun. They can also use them to direct the sun’s heat either onto or away from their bodies. These butterfly species have either growing or stable populations.
On the other hand, more colorful larger butter species, like Red Admiral (Vanessa atalanta) and Peacock (Aglais io) find it difficult to control their body temperature. Butterfly wings also come in different colors and they use it more than just to enable flight. Their colors and patterns serve as a form of mimicry or camouflage and the fine scales keep them insulated during cold months.
In the recent study, the researchers found that some butterfly species depend on finding a location at a certain temperature within a landscape to control their body temperature. They refer to it as the microclimate. Although the climate in such a spot differs from those in the surrounding areas, the area is usually very small. The air temperature in the area differs on a fine scale. For example, the shaded patch of ground is cooler compared to those exposed in full sun.
The authors found that some species classified as “thermal specialists,” such as the Small Copper (Lycaena phlaeas) and Brown Argus (Aricia agestis) have suffered bigger population declines in the last 40 years. These species may be at risk from landscape homogenization, which is a process of making the area similar to that of cities or towns. Future conservation attention should be focused on these species, their study reads.
Butterflies as ectotherms
All butterflies are ectotherms, whose regulation of body temperature relies on external sources, such as a heated rock surface or sunlight, and they cannot generate their body heat. About two-thirds of UK butterfly species are now in decline, reports Science Daily. A more monotonous landscape, fragmentation, and habitat loss have removed many of the microclimates that butterflies needed to survive. Added to the concern is climate change that is causing greater variations in temperature and extreme weather events.
Dr. Andrew Bladon, a Postdoctoral Research Associate from the Department of Zoology, told Science Daily that butterfly species that are likely to suffer the most from habitat loss and climate change are those who rely on micro-habitat at the right temperature for their body.
The monarch butterflies, one of the most well-studied and recognizable butterflies on the planet characterized by their orange wings laced with black lines and bordered with white dots, also appears to be declining. As published by the nonprofit educational outreach program Monarch Watch, the total area occupied by monarch colonies at overwintering sites records an all-time low of 0.67 hectares in 2014 from 20.97 hectares in 1997.
In 2002, 2004, and 2010, massive Pacific weather impacted central Mexico and each of these events resulted in high winds, heavy rain, and freezing temperatures that devastated the monarch overwinter populations. Another factor for their decline is the loss of habitat in the summer breeding grounds. About 6,000 acres of potential pollinator or monarch habitat a day is lost in the US due to development. The Monarch Butterfly Biosphere Reserve (MBBR) also shared that the eastern North American monarch colonies for winter occupied 6.05 hectares in 201 from 2.48 hectares in 2018.
Percentage decline in selected global insect populations over the past decade
Fifty-three percent of the global butterfly populations are in decline over the past decade but they are not the only insect population affected. Other global insect populations in decline over the past decade include caddisflies (68%), beetles (49%), bees (46%), mayflies (37%), dragonflies (37%), stoneflies (35%), and flies (25%).
To protect monarch butterflies, conservationists recommend people not to use pesticides anywhere on land. Not only does it kill any type of insect larvae, including butterflies, but they also contain glyphosate that destroys milkweed. What’s alarming is that it is the only plant that monarch butterflies can lay their eggs in. The leaves of milkweed are also the sole food that is eaten by the monarch’s larvae. This means that killing off milkweed destroys the monarchs forever.
If you have a yard, it is also advised to have a part of it get overgrown and fill it with milkweed plants. Provide a butterfly-safe watering dish for the little ones to drink. This also ensures that butterflies have a safe place to rest, stop, and regroup during migration.
Ethnobotanist and herbalist Catherine Winter, who is not involved in the study, recommends purchasing only FSC-certified wood. The Forest Stewardship Council (FSC) is a nonprofit organization that sets standards to ensure that forestry is practiced in a socially beneficial and environmentally responsible manner. If a piece of hardwood is labeled as FSC certified, it means that the manufacturer and the wood used met the requirements of the organization.
The ethnobotanist added that monarch migrates to Mexico for the winter but the illegal country has destroyed the places where these butterflies gather. She encourages everyone to do their part to combat climate change by reducing the waste we create, making sure that our home is energy-efficient as possible, and to drive less.
With the new understanding of butterflies, it can help the world better manage landscapes and habitats to protect them. In so doing, we are also indirectly protecting other insects.