The grasshopper is a common insect found in grasslands and gardens worldwide. Like many insects, grasshoppers conceal signs of illness or weakness to avoid predation. This instinct means that by the time a grasshopper shows noticeable distress, its decline is often far advanced and death is imminent. Determining if a grasshopper is dying requires careful observation of subtle shifts in its typical behavior and physical condition.
Behavioral Indicators of Distress
A healthy grasshopper is characterized by rapid, explosive movement and constant activity. Any significant change in its mobility is a strong indicator of severe distress. One common sign is profound lethargy, where the insect remains motionless even when approached, or responds with only a slow, sluggish hop rather than a vigorous leap. This lack of a strong escape response signals a depletion of energy reserves or a failure of the neuromuscular system due to disease or poisoning.
Infected individuals often display a dramatic reduction in typical activities such as feeding and grooming. When movement does occur, it may be severely uncoordinated, manifesting as erratic walking, tumbling, or an inability to properly right itself if it lands on its back. A striking behavioral indicator of a terminal fungal infection, known as “summit disease,” involves the grasshopper climbing to the highest point of vegetation just before death. The fungus manipulates this ascent, causing the insect to die while rigidly clinging to the stem, which aids in spore dispersal.
Physical Manifestations of Illness or Injury
Physical manifestations provide direct visual evidence of internal or external damage. Visible physical trauma, such as a missing leg or a damaged wing, prevents the grasshopper from escaping predators or locating food, leading to a rapid decline. Diseases can also produce specific visual cues, such as the white, fuzzy growth that may appear on the body of a grasshopper infected with the Entomophaga grylli fungus after death.
A notable physical sign of advanced illness is an unnatural posture, such as a curled or distended abdomen, or a tendency to lie on its side. Discoloration, including unusual darkening or paleness of the exoskeleton, can suggest systemic internal infection or dehydration. External parasites, like the bright red larvae of the red locust mite (Trombidium locustarum), can be seen attached to the body, visibly draining the insect’s hemolymph, or “blood,” and causing a slow demise.
Primary Causes of Grasshopper Mortality
Decline is typically rooted in a few primary causes, with pathogens being a significant factor. Fungal diseases are common, including Entomophaga grylli, which causes the characteristic climbing behavior to optimize spore distribution. Other fungi, such as Beauveria bassiana, can infect the host, though grasshoppers sometimes combat this by basking in the sun to raise their body temperature.
Parasitic infections are another major cause of death, where an internal organism consumes the host from within. Hairworms (nematodes) infect grasshoppers, developing inside the body cavity for weeks before the mature worm exits, a process lethal to the host. Similarly, parasitic flies lay eggs on the grasshopper’s body, and the resulting larvae burrow inside to feed, eventually killing the insect.
Severe physical trauma, often resulting from failed predation attempts by birds or spiders, can lead to fatal injuries even if the grasshopper initially escapes. Finally, exposure to chemical agents, such as insecticides, is a rapid cause of death, as these neurotoxins quickly lead to a failure of the nervous system and motor function. This poisoning results in sudden and total immobility, which is often observed as the insect trembles or is found unable to move.