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Predatory Bugs
often found in gardens and crops

Bugs are a large group of insects which includes many pests of plants. There are however many bugs that are important predators of other insects. They range in size from the minute Orius to the ferocious Assassin bug.

They undergo a gradual metamorphosis usually through five instars in which they shed their skins in a series of molts until adult hood when they develop wings. Unlike beetles there is no pupal stage.

Minute Pirate Bugs - Orius spp.

Primary Hosts: moth eggs, aphids and thrips

Key identifying characteristics:
The tiny predatory bugs (about 2.5 mm long) predominately black with light wing patches, are found in many crops. Their tiny eggs are rarely seen as they are laid singly into plant tissue.

Nymphs are yellow-orange or brown tear shaped (top right). Orius feed on Heliothis eggs, thrips and may feed on Dried Fruit Beetle eggs and larvae. They are first encountered in the tassels and then in the silks.

Significance:
These are major predator in some areas. What constitutes a significant number is unclear but current studies indicate that two per silk in sweet corn will have a significant impact on a moderate heliothis egg lay.

Orius are now mass reared - More info

Big Eyed Bugs - Geocoris spp. and Germalus spp.

Primary Hosts: Soft bodied insects and mites

Key identifying characteristics: They are broader and slightly larger than Orius at about 3 mm long and distinguished by their very large eyes.

Significance: These bugs are not nearly as abundant as Orius in the Lockyer Valley but are found in most crops.

Damsel Bugs - Nabis kinbergii

Primary Host: Soft bodied insects, moth eggs, small larvae and mites

Key identifying characteristics: adults slender, about 8 mm long, pale brown, narrow head with large eyes and long antennae.

They are a fast moving general predator which feeds on moth eggs and small larvae. In the pre tassel stage of corn they are often seen in the whorl, then the tassel and latter around the cob and silk area.

Damsel bugs move quickly when disturbed.  

Significance: Damsel Bugs were very common in corn in the Lockyer Valley SE Qld- at times close to one per plant.

They are important predators in vegetable crops especially brassicas where they feed on cabbage moth larvae.

Damsel bugs are mass reared - more info.

Black Mirid - Tytthus chinensis

Primary Hosts are moth eggs.

Key identifying characteristics:
Adult, about 4 mm long, fast moving, dark bodied, pale legs, relatively large eyes, long antenae.

Significance: very common and significant in some crops and growing areas.

Predatory Shield Bugs

Primary Hosts are small to large caterpillars

Key identifying characteristics:
Horn like protrusions, shield shaped body with overlapping wing tips, extended mouth parts.

Very common in some areas while absent in others. They are voracious feeders and attack even large grubs.

Assassin Bugs, various species

Primary Hosts are small to large larvae

Key identifying characteristics:
12 to 18 mm long, curved beak is held beneath the narrow head. Long front legs for grasping its prey.

Sometimes seen in corn crops but not as common as the other predatory bugs mentioned above. More common in tree fruit crops.

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Big eyed bug adult

Orius adult - minute pirate bug

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Damsel bug adult

Black mirid - predatory bug

┬ęDenis Crawford/Graphic Science

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Assassin bug nymph

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Predatory shield bug attacking large caterpillar

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Assassin bug adult

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Predatory shield bug

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┬ęDenis Crawford/Graphic Science