beneficials

Scientific name: Microvelia douglasi atrolineata Bergroth

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Common name: Water bug

Class: Insecta
Order: Hemiptera
Family: Veliidae
Generalist predator.
Leafhoppers and planthoppers.
Microvelia douglasi atrolineata is a short but broad small water bug. It is black with small gray areas. It exists in two forms, winged or wingless. The wingless adults have no black and white markings on the neck and front wings.

These water bugs can be distinguished by their broad shoulder and 1-segmented front tarsus. Their claws are anteapical.

Both the adults and nymphs live on the water surface and attack insects that fall onto the surface. They are more successful as predators when they attack the host in groups. A single water bug feeds on small nymphs, whereas a group of Microvelia will attack larger prey. The water bugs use their mouth parts to inject a toxic solution to paralyze the prey. A single predator feeds on 4 to 7 hoppers daily.

A female water bug can lay 20 to 30 eggs in rice stems above the water surface in her life span of 1 to 2 months.
Microvelia douglasi atrolineata can survive for long periods even without food provided the field is saturated or flooded.

 

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The broad-shouldered adults of water bug Microvelia douglasi atrolineata Bergroth 

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Nymph of Microvelia douglasi atrolineata

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Water bugs feeding on hoppers on the water surface

Selected references

Barrion AT, Litsinger JA. 1994. Taxonomy of rice insect pests and their arthropod parasites and predators. In: Biology and management of rice insects. Manila (Philippines): International Rice Research Institute. p 13-362.

Reissig WH, Heinrichs EA, Litsinger JA, Moody K, Fiedler L, Mew TW, Barrion AT. 1986. Illustrated guide to integrated pest management in rice in tropical Asia. Manila (Philippines): International Rice Research Institute. p 13-362.

Shepard BM, Barrion AT, Litsinger JA. 1987. Helpful insects, spiders, and pathogens. Manila (Philippines): International Rice Research Institute. 127 p.