Variegated grasshopper

The variegated grasshopper (Zonocerus variegatus) is a significant insect pest belonging to the order Orthoptera and the family Pyrgomorphidae. Widely distributed throughout tropical Africa, it is notorious for its polyphagous nature and its tendency to occur in dense swarms that wreak havoc on local agriculture.

This species is highly destructive to various economically important crops, including cassava, cocoa, coffee, citrus, cotton, and maize. Due to its broad diet, it can move from wild host plants to agricultural fields, causing substantial yield losses. In cases of severe infestations, complete defoliation of trees and crops is common.

The life cycle consists of the egg stage, five nymphal instars, and the adult stage. Eggs are laid in the soil, often in specific sites that become communal hatcheries. As nymphs mature through their five instars, they exhibit distinctive yellow and black warning coloration. They derive chemical defenses from the plants they consume, rendering them unpalatable and toxic to many potential predators.

Damage is characterized by extensive chewing of leaves, stripping of bark, and consumption of tender shoots. Beyond the physical loss of biomass, the grasshoppers deposit secretions and feces on the crops, which can lower the market quality and invite secondary fungal pathogens. The collective feeding behavior allows them to destroy a field in a matter of days.

Integrated Pest Management (IPM) for this grasshopper involves cultural practices such as tilling the soil to expose egg pods to desiccation and predators. Farmers are also encouraged to clear weeds that serve as early-season food sources for nymphs. Chemical control is usually reserved for major outbreaks, focusing on nymphal stages before they develop wings and become highly mobile.

• Deep ploughing to disturb egg pods in the soil.
• Mechanical collection and destruction of nymphs.
• Removing weed hosts near farm boundaries.
• Application of contact insecticides during early instar stages.
• Using botanical pesticides as a sustainable alternative.