The dragonfly spends the vast majority of its life underwater as a nymph. Once it emerges as a winged adult, its lifespan is brief, often lasting only a few weeks to a couple of months, depending on the species. Determining the health status of these aerial predators can be challenging. Their small size and rapid metabolisms mean that a decline progresses quickly, making it difficult to distinguish between a healthy insect resting and one facing its final moments.
Observable Indicators of Decline
A declining dragonfly exhibits pronounced physical and behavioral signs. A clear indicator is extreme lethargy, where the insect remains stationary for extended periods and shows little to no response to external stimuli. This contrasts sharply with a healthy dragonfly’s naturally alert and reactive nature.
Physical signs of advanced age or severe injury are often visible on the wings. While minor fraying is common, a dying dragonfly may have wings that are tattered, crumpled, or missing significant portions, sometimes up to 75% of the total area. This kind of severe wing damage drastically impairs flight performance, making foraging for food and escaping predators nearly impossible.
Dragonflies experience changes in body condition over their short adult lives. Studies note an age-related decline in both body mass and the width of the thorax, indicating a weakening physical state. Additionally, some species may display a noticeable fading or discoloration of their vibrant body colors, transitioning from bright hues to a duller shade as they approach the end of their lifespan.
Factors Contributing to Mortality
The most common reason for a dragonfly’s decline is the natural end of its short adult life cycle. Biological aging causes a gradual loss of physical capabilities, eventually leading to death within its expected lifespan. Injuries that reduce flight ability also represent a frequent cause of mortality, often stemming from accidental collisions with vegetation or aggressive territorial clashes with other dragonflies.
Predation attempts, even unsuccessful ones, can leave a dragonfly with debilitating injuries such as damaged wings or missing legs. Environmental pressures like sudden, prolonged cold weather can cause internal systems to shut down, while poor foraging conditions may lead to starvation. Furthermore, human factors like exposure to widespread pesticides or fatal collisions with motor vehicles near aquatic habitats contribute to the sudden loss of adult dragonflies.
Interpreting Behavior Resting or Dying
It is easy to mistake a resting dragonfly for one in distress. A healthy dragonfly often enters a state of reduced activity known as basking, sitting still with its wings spread to absorb solar energy and warm its flight muscles. This warming is necessary because dragonflies are cold-blooded and require high body temperatures for flight.
To discern between rest and decline, look for the insect’s posture and control. A resting dragonfly maintains a firm grip on its perch, and its wings, though still, are held outward in their characteristic “airplane” position. A truly distressed or dying dragonfly, however, may be found lying on its back or side on the ground, exhibiting an inability to right itself due to weakness or neurological damage. If the insect cannot walk or fly correctly when gently prodded, or if it is trembling uncontrollably, it is likely in the final stages of decline.