Lifesaving Role of Trees in Insect Flood Survival

Introduction

When floods occur, the landscape changes dramatically as water engulfs everything in its path. Larger animals, such as birds and mammals, can either fly away or run to higher ground. However, for smaller creatures like insects, survival becomes more complex. Many insects find refuge in trees, relying on them for food, shelter, and protection from predators. Trees, in turn, serve as vital survival havens during floods, supporting both the ecosystem and the biodiversity of the environment. In this post, we will explore how trees play a crucial role in helping insects adapt and survive when faced with flooding.

How Trees Help Insects During Floods

Tree Canopy Refuge

The tree canopy, or the uppermost layer of leaves and branches, provides a natural refuge for insects during floods. Insects that can fly, such as bees, butterflies, and dragonflies, use the canopy to escape rising floodwaters. The dense foliage and structure of trees offer protection from both the water and predators that may also be fleeing the flood.

This elevated zone not only keeps insects safe from drowning but also offers resources like food (nectar and leaves) and shelter. The canopy acts as a micro-habitat, where insects can continue their life cycles relatively undisturbed. The availability of different plant species and the variation in canopy structure among trees make the canopy a crucial survival zone for various insect species.

Egg-Laying Strategies

Many insects have evolved clever ways to ensure the survival of their offspring during floods. One common strategy is laying eggs in elevated locations such as treetops or on branches, where they are less likely to be washed away. Some species, like mosquitoes, lay eggs on the surface of still water, which may get dispersed during a flood, aiding the species in finding new habitats. Others, like water beetles, lay their eggs underwater in flood-prone areas, allowing the eggs to survive until the floodwaters recede.

Insects that live in flood-prone areas may also time their egg-laying with expected flooding. For instance, mass emergence is a strategy where entire populations of insects emerge after a flood, taking advantage of the nutrient-rich conditions left behind.

Larval Adaptations

Insect larvae have developed a range of adaptations to survive floods. Aquatic larvae, such as those of mosquitoes or dragonflies, can live submerged in water for extended periods. For tree-dwelling species, the larvae might use waterproof egg cases to protect themselves from moisture or seek out higher places within the tree, like branches or crevices, to avoid flooding.

Some larvae can also migrate within the tree, moving to drier areas as floodwaters rise. Others, like wood-boring beetles, may bore deeper into the tree’s structure, where they remain unaffected by external water conditions. These adaptations ensure that even in times of flooding, the larvae can continue their development, eventually emerging as adults once conditions improve.

Pupation and Metamorphosis

For many insects, the pupal stage—where they undergo metamorphosis into adult forms—offers protection from environmental challenges, including flooding. Insects that pupate inside trees, such as wood-boring beetles and some moth species, construct protective cases or cocoons that shield them from water and other hazards. These waterproof structures allow the insect to complete its transformation safely, emerging once the flood has passed.

Some species may delay their pupation until the water recedes, avoiding the worst of the flood. Insects that pupate within trees also benefit from the tree’s natural defenses, such as its thick bark and dense wood, which provide additional protection from external threats.

Climbing Behavior

During floods, many insects instinctively seek higher ground to avoid drowning. Species like ants, spiders, and beetles use their natural climbing abilities to reach higher branches, leaves, or the tree trunk, where they are safe from the floodwaters below. In more extreme cases, ants have been observed linking together to form rafts, floating on the surface of the water until they can find a safe place to land.

Some spiders will spin silk threads that anchor them to the tree, acting as safety lines that keep them from being washed away. Aquatic insects, like water striders, use the surface tension of the water to float, allowing them to survive even in flood conditions.

Tree Bark and Wood as Shelters

Insects that burrow into tree bark or wood, like wood-boring beetles or termites, have an added advantage during floods. The solid structure of trees serves as a natural barrier against floodwaters. Insects hidden inside the tree are insulated from the water and can continue their lifecycle uninterrupted.

The tree’s bark, with its many cracks and crevices, also provides shelter for insects seeking refuge from the flood. These tiny spaces offer protection from predators and allow insects to cling to the tree until the floodwaters subside.

Life Cycle Adjustments

Some insects have evolved life cycle adjustments to help them cope with flooding. Species that live in flood-prone areas may enter a state of dormancy, known as diapause, to survive until conditions improve. For example, certain insect larvae, such as mosquitoes, delay their emergence until floodwaters recede, ensuring they hatch in more favorable conditions.

Other species, like caddisflies and dragonflies, are adapted to live in temporary aquatic habitats and can thrive in areas affected by floods. These adaptations allow them to take full advantage of post-flood environments, which are often rich in nutrients and newly available habitats.

Elevation and Shelter

The height of trees above floodwaters offers a distinct advantage to insects that can climb or fly. During floods, insects often seek refuge in the higher branches of trees, where they are protected from rising water levels. Wasps, bees, and ants are examples of species that will cling to trees or build temporary shelters in elevated areas, keeping themselves safe from the flood.

In some cases, entire colonies of ants have been known to use trees to create “living rafts,” floating through floodwaters until they reach a safe, dry location.

Food and Shelter Availability

Even during a flood, trees continue to provide food and shelter for insects. Many species feed on the leaves, nectar, and sap that trees produce, allowing them to sustain themselves even in challenging conditions. The cracks in bark, spaces between leaves, and the dense foliage of trees also offer protection from predators and strong currents, giving insects a place to hide during the flood.

Slowing Water Currents

Trees act as natural barriers during floods, helping to slow down the water flow. This creates pockets of slower-moving water around tree trunks, branches, and leaves, where insects can safely avoid the stronger currents. By reducing the speed and force of the water, trees provide a safer environment for insects to cling to or find refuge in.

Trees also help reduce the amount of surface runoff and improve the infiltration of rainwater into the soil. This not only benefits the ecosystem by preventing erosion but also creates safer micro-environments for insects during floods.

While not all insects can survive floods, many species have evolved remarkable adaptations to endure these natural disasters. Trees play an essential role in this survival, offering shelter, food, and refuge from predators and rising waters. By providing these resources, trees support the resilience and biodiversity of insect populations, even in the face of environmental challenges like floods.

References:

^[1]Team, H. I. W., & Team, H. I. W. (2019, July 9). How insects survive floods. How It Works. https://www.howitworksdaily.com/how-insects-survive-floods/^[2]How to manage flood damage to trees. (n.d.). UMN Extension. https://extension.umn.edu/planting-and-growing-guides/how-manage-flood-damage-trees^[3]Goodwin, M. (2017, June 29). Trees can Reduce Floods – The Institute of Chartered Foresters. The Institute of Chartered Foresters. https://www.charteredforesters.org/trees-can-reduce-floods^[4]Wikipedia contributors. (2023, September 12). Canopy (biology). Wikipedia. https://en.wikipedia.org/wiki/Canopy_(biology)^[5]Europe PMC. (n.d.). Europe PMC. https://europepmc.org/articles/PMC4648384/