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In general, vegetable insect pests have chewing or piercing-sucking mouthparts. Caterpillars, beetles, and grasshoppers are good examples of insect pests with chewing mouthparts. Large stink bugs and leaffooted bugs are some “macro bugs” with piercing-sucking mouthparts. On the contrary, various species of aphids, thrips, and whiteflies are “micro bugs”.

  • Unlike moths and caterpillars that are very common in rural areas and may take several years for population buildup, macro bugs like stink bugs and leaffooted bugs are active in both rural and urban farms. Leaffooted bugs belonging to the genus Leptoglossus have now become the dominant sucking insect pests in vegetable fields and fruit orchards.
  • Stink bugs and leaffooted bugs are highly migratory and breed rapidly initially on the field edges. Thereafter, the bugs may become more prolific throughout the field as overlapping generations and various life stages feed together.
  • While the adults are distinct looking and typically found in small numbers feeding or mating on host plants (except leaffooted bugs that may form large aggregations), nymphs stay together in the early stages and scatter out at later stages. Nymphs (pest species) are easiest to recognize when they are in masses under plant parts.
  • Stomach insecticides, especially the organic ones, are usually ineffective against the macro bugs since they do not consume toxic doses of those insecticides. Therefore, sucking insect pest management generally involves heavy use of broad-spectrum contact insecticides that can also kill beneficial insects. This is the reason organic producers should have alternative landscape-level IPM tactics for pest management. Keep records of all IPM successes and failures as research data is lacking for many organic insecticides.
  • How would you tell whether a nymph is from a pest or beneficial species? Nymphs of beneficial species disperse rapidly upon hatching from eggs (e.g., assassin bugs) in search of prey that includes small caterpillars, leafhoppers, and other smaller insects. Beneficial insects generally hunt singly while perched on top of leaves or branches.  Pest species stay together in masses usually hidden under plant parts. They tend to scatter when disturbed. Identify bugs from anatomical details as well as their behavior before making any treatment applications. Use the image on top as a field guide for identifying some of the major adults and nymphs.

Management

  • Use prevention tactics first.
    • Timely planting and harvest can reduce quality loss of produce.
    • Trap crops for field crops and pest exclusion system for high tunnels can reduce crop losses.
  • Conventional insecticides – many synthetic pyrethroids (Mustang Max, Karate, Brigade) are effective; neonictinoid insecticides like Venom or Scorpion also work well although there can be use restrictions on the labels that must be followed.
  • Organic insecticides – kaolin clay can act as a deterrent; natural pyrethrin and spinosad products are effective against nymphs infesting the main crops or trap crops.

 

 

Featured Image of Brown Marmorated Stink bug by Susan Ellis, Bugwood.org

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