WSU Extension

Hortsense

Predatory Bugs
 
Ambush bugs 
Assassin bug 
Big-eyed bugs 
Damsel bugs 
Minute pirate bugs 
Mirids 
Stink bugs 



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Caption: Adult assassin bug (Rhynocoris ventralis) (Reduviidae)
Photo by: D.G. James
  
Predatory Bugs : Assassin bug
(revision date: 10/3/2018)


Biology
Assassin bugs are blackish, brown, or reddish with a long, narrow head; round, beady eyes; and an extended, three-segmented, needle-like beak. The front legs are enlarged for grasping prey. They are larger (2/5 to 4/5 inch) than other predatory bugs. Eggs are reddish-brown, skittle-shaped, and laid in a batch or raft of 10 to 25 or more. The eggs are coated with a sticky substance for protection. Nymphs are small versions of adults, although early instars are often ant-like. Assassin bugs are long-lived predators and consume large numbers of small insects and mites during their lifetime. Adults may live for more than one season and nymphs are slow to develop. Population densities of assassin bugs are usually low but they provide useful, consistent, and long-term feeding on leafhoppers, beetles and caterpillars in gardens.

Prey or Pest Targeted
  • Mites, aphids, leafhoppers, thrips, caterpillars, mealybugs, beetles, scale insects, insect eggs
     
Attracting and Keeping Natural Enemies & Pollinators in Your Yard
  • Avoid regular use of synthetic, broad-spectrum pesticides. Infrequent use of certain narrow-spectrum pesticides is more compatible with some beneficials but generally the less chemical inputs there are, the greater and more diverse the beneficial insect community will be. Extensive lawns are also not conducive to attracting and retaining a diversity of beneficial insects, mites and spiders. Minimize lawn areas and maximize shrub and bush plantings. Many beneficials reside naturally in riparian and other ‘natural’ areas near to many back yards. Natural dispersion from these refuges ensures that some beneficials will visit back yards but they will not stay unless food, host and shelter resources are available. Native plants have closer affinities with native insects and therefore provide most of these resources. A garden with a good diversity of local native flora in and around back yards, will improve the abundance and diversity of local, beneficial arthropods. Native flora also provides natural overwintering sites for many beneficial insects and it is useful to leave at least a small area of native vegetation undisturbed during fall and winter.
  • Some kinds of beneficial insects (e.g. lady beetles, lacewings, predatory mites) are available for purchase from commercial suppliers. However, benefits from introducing these beneficials are usually limited and short-lived. Upon release, commercially obtained lady beetles and lacewings often disperse and may rapidly leave your backyard despite the presence of prey and suitable nectar resources. Generally, it is more effective and sustainable to create a garden habitat that will be colonized by beneficials naturally.
     

Images

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Caption: Adult assassin bug (Rhynocoris ventralis) (Reduviidae)
Photo by: D.G. James
Caption: Egg raft of assassin bug (Rhynocoris ventralis) (Reduviidae)
Photo by: D.G. James