Where Do Dragonflies Go in the Winter?

Where Do Dragonflies Go in the Winter?

Different kinds of dragonflies have their own method for surviving.

As summer wanes into autumn and the cooler weather starts to roll in, what happens to the dragonflies that hatched out of our local waterways over the last few months? Well, the answer is a little bit different for each species.

These insects (and many more) spend a portion of their lives in the water. Dragonflies are a good indicator of water quality as some species are more tolerant of pollution and others are very intolerant of pollution. Many aquatic insects also have very specific habitat needs, so knowing which groups are found in a stream and which ones are missing helps guide restoration projects.

Laying Low During the Winter

During the summer months, dragonflies emerge from their aquatic larval stage, stretch out their wings and take flight. Females and males tend to use different habitats until it is time to mate. Here is where some species differ in their approach to surviving winter – some lay eggs in the water that will hatch, grow underwater through the summer, slow down for the winter and then emerge as adult dragonflies the next summer. Some of these species may stay in the aquatic larval stage for several years before emerging as adults, like the federally endangered Hines Emerald Dragonfly that is found in parts of the Des Plaines River Watershed.

Other species of dragonflies and damselflies will lay eggs that survive the winter and hatch the next spring or summer. They lay their eggs in vegetation or damp logs along the edge of a pond that will be inundated in the fall or spring, triggering the eggs to hatch and start the larval journey. The Swamp Darner uses this tactic, laying its eggs in logs in ephemeral ponds that dry out in the summer and fill back up in the spring.

Many other aquatic insects follow this same life cycle. They emerge as adults in the spring or summer and either lay eggs that hatch and spend the winter in the larval stage or lay eggs that overwinter and hatch the next spring or summer.

Did You Know Some Dragonflies Migrate?

One strategy to surviving the winter that we don’t usually think about when it comes to dragonflies is heading south for the winter! A few species of dragonflies actually migrate – the most common one is the Green Darner, a large, colorful dragonfly.

Like the Monarch Butterfly, the Green Darner migrates over three generations. They emerge from waters in the Gulf Coast, Florida and the Caribbean and fly upwards of 400 miles to the north where they lay eggs and die. The eggs hatch, the larvae grows and emerges in mid to late summer. These adults form large groups and fly back south where they lay eggs and die. Another generation grows, emerges, lays eggs in the south and dies without migrating at all. This last set of eggs will hatch out and travel back up north, starting the process all over again.

Different species of dragonflies tolerate different levels of pollutants in a stream or have different habitat requirements. Because of this, dragonflies are important indicators of waterway health.
Some dragonflies spend the winter underwater in their larval stage. Other dragonflies lay eggs that survive the winter and hatch the next spring or summer.
A few species of dragonflies, like the Green Darner, migrate south for the winter and lay eggs. This next generation stays in the south for its entire life cycle. The third generation will migrate back north.

Do Dragonflies Migrate or Hibernate? (Surviving Winter)

Most species of dragonfly spend the winter in their larval form, or as an egg. Generally, the adults will die off, and the young with either continue feeding below the surface of the water or enter diapause, a type of hibernation. Some dragonflies also migrate.

How do dragonflies survive the winter?

Dragonflies are a type of insect, which means they are cold-blooded. Unlike mammals, which are warm-blooded, insects don’t create their own heat (aside from a small amount generated by movement). This means they need to make use of the warmth of the sun. At night and in winter, the lack of external heat means they have to develop clever strategies to survive.

Given this particular set of constraints, how do dragonflies get through the winter? They can use a number of different techniques, which range between species, and even sometimes within them.

Dragonflies that overwinter as eggs

Many dragonflies overwinter as eggs. These eggs are laid usually at the end of summer after the adults have mated. Some dragonfly species can lay their eggs directly in the water, where they may sink to the bottom or become attached to aquatic plants. Other species may lay their eggs outside the water, such as in slits the female dragonflies make in vegetation.

These eggs either enter diapause, which is a type of hibernation, or hatch out into larvae. Entering diapause means they will stop developing until the weather warms, meaning they will spend the winter in an egg form, not developing any further.

There are benefits of remaining as an egg throughout winter. This is a hard time when food is scarce. The small eggs are easily hidden from hungry scavengers and require little energy use throughout this time. The downside is that the egg is not able to move, meaning that if conditions change, and become unsuitable for the egg, it may die.

Dragonflies that overwinter as larvae

Larvae are juvenile dragonflies, and can also be called nymphs. They live within the water and spend their time hunting smaller invertebrates. Many dragonflies species overwinter in the water as larvae. This is in part because water temperatures take longer to lose the warmth of the summer sun, keeping warmer for longer. Additionally, as long as the water is deep enough, ice may form on the top, insulating the water beneath.

Overwintering as a larva has the added advantage that the dragonfly can move around and feed. This means it can continue to grow throughout the winter, and also change locations if conditions worsen. The downside is that larva also makes a tasty snack for other species, and are harder to hide than a tiny egg.

Not all larvae remain active over winter. Some larvae may enter diapause. This means they can cope with the cooler condition and are not growing, so do not need to hunt for food. Many dragonfly species can spend several years as larva, and therefore spend many winters living as juveniles within pools or watercourses.

Do dragonflies hibernate as adults?

In many insects, the main aim of their adult form is to produce offspring. Most dragonflies will spend the largest proportion of their lives as larvae, only becoming an adult for a few weeks or months. Within this time they will feed and hunt but their main aim is usually to defend a territory and bag a suitable mate.

Once mating is complete, and the eggs are safely laid, their life’s work is completed. They aren’t designed to have a second go the following year, meaning that the adults tend to die by the end of the summer, not needing to enter hibernation.

Dragonfly migration

Although we have been aware that many species of dragonflies migrate for over a century, the migration of dragonflies is still little understood. This is in part because the migration of small insects is more difficult to observe and track than that of larger animals like birds and mammals.

Only a small proportion of species migrate, with most only moving a small way from where they emerge from their larval form into the adults. More confusingly, within some species, there are populations that migrate and others that don’t.

These two populations may even use the same areas, simply employing different strategies for coping with the approach of winter.

Dragonfly migration takes place on every continent aside from Antarctica. Within the UK the majority of the migrants come in from mainland Europe. These migrants tend to arrive for the summer, and breed in the UK. Species include those which are already resident in the UK, such as the migrant hawker, or others that are not usually found here, such as the lesser emperor.