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Soldiers in Our Gardens

How to Identify, manage, and attract beneficial insects

Insects … ugh! What to do?

by Judy Quan

Question to the Help Desk: “What are these flying insects? I am hoping you can identify them and let us know how to get rid of them?”

That is the reaction of most people when they see insects, “How can I get rid of them?” Insects need a second look. There are the good guys and the bad guys. The flying insect pictured above with the red head and black “wings” is a soldier beetle, often also called a leatherwing, part of the Cantharidae family. There are over 100 species of beetles in California. These distinctive “uniforms” formed by their red bodies and black wing covers are a welcome sight to many gardeners. They are part of the good guys, beneficial insects feeding on the pests in the garden.

Beneficial insects, the good guys

Surprisingly, most gardens have far more good guys (beneficial insects) than bad guys (pest insects). Beneficial insects feed on pests, controlling them naturally. There are more pollinators than just bees; beneficial insects, like the soldier beetle, also pollinate plants.

Soldier Beetles are just one kind of beneficial insect

Soldier beetles, just one kind of beneficial insect, have a voracious appetite for aphids, caterpillars, grasshopper eggs, mites, and other small pests. Soldier beetles are a wonderful natural way to control aphid pests in the garden.

In my garden, the soldier beetles have helped me control scale on my mandarin orange tree. They fed on the immature scale in the citrus, though most often this beneficial insect feeds mostly on aphids, pollen or nectar. A hundred or so of the beetles were there for a few days and then they were gone.

If you are as fascinated as I was, here are some links to information and photos of soldier beetles that I found helpful.

Beneficials and Integrated Pest Management (IPM)

Integrated Pest Management (IPM) combines environmentally sound ways to prevent and manage pests minimizing harm to people and the environment. According to UC IPM Quick Tips for IPM and Beneficial Insects:

  • We can change the garden environment to discourage pests while promoting the presence of good bugs.
  • Many pests can be controlled without the use of pesticides.
  • We can encourage the good bugs to hang out in our gardens and eat garden pests, reducing the need for insecticides that end up in our waterways.
  • Learn to identify good bugs in their mature and Immature (larvae) stages

Ways to identify beneficial insects

Learning to recognize some natural enemies of garden pests is easy if you have a visual guide.

Have a look at UC IPM's educational poster, "Meet the Beneficials: Natural Enemies of Gardens".

You may examine more photos of beneficial insects to encourage in the garden on the UC IPM's Beneficial Predator resource page. Some examples include "baby" pictures too. While these images may not be as cute as your childhood school photos, they are very helpful in aiding the identification of beneficials in your garden when they are eggs or juvenile versions of their adult selves. 

Ways to encourage beneficial insects to be in your garden

  • Encourage beneficial insects by avoiding pesticides since pesticides can kill both the good guys and the bad guys.
  • Choose plants that provide beneficial insects with pollen, nectar, and shelter.
  • Keep ants out of pest-infested plants. Ants will attack beneficial insects to protect pests like scale and aphids that excrete honeydew, a sugary liquid, which is a source of food for the ants.

Other beneficial insects, “natural enemies” and biological control

Biological control is the use of parasites, pathogens, and predators (natural enemies) in managing pests. The following table from UC IPM contains a listing of some pests and their common natural enemies. Common natural enemies include lacewings, lady beetles, parasitic flies, parasitic wasps, and predatory mites. 

PESTS Lacewings Lady beetles Parasitic flies Parasitic wasps Predatory mites Other Groups and Examples
aphids X X   X   entomopathogenic fungi, soldier beetles, syrphid fly larvae
carpenterworm, clearwing moth larvae       X   entomopathogenic nematodes
caterpillars (e.g., California oakworm) X   X X   Bacillus thuringiensis, birds, entomopathogenic fungi and viruses, predaceous bugs and wasps, Trichogramma spp. (egg parasitic wasps), spiders
cottony cushion scale   X X     Cryptochaetum iceryae (parasitic fly), vedalia beetle
elm leaf beetle     X X   Erynniopsis antennata (parasitic fly), Oomyzus (=Tetrastichus) spp. (parasitic wasps)
eucalyptus longhorned borers       X   Avetianella longoi (egg parasitic wasp)
eucalyptus redgum lerp psyllid       X   Psyllaephagus bliteus (parasitic wasp)
giant whitefly X X   X   Encarsia hispida, Encarsia noyesi, Entedononecremnus krauteri, and Idioporus affinis (parasitic wasp), syrphid fly larvae
glassy-winged sharpshooter X     X   assassin bugs, Gonatocerus spp. (egg parasitic wasps), spiders
lace bugs X X   X   assassin bugs and pirate bugs, spiders
mealybugs X X   X   mealybug destroyer lady beetle
mosquitoes           Bacillus thuringiensis spp. israelensis, mosquito-eating fish
psyllids X X   X   pirate bugs
scales X X   X X Aphytis, Coccophagus, Encarsia, and Metaphycus spp. parasitic wasps
slugs, snails     X     Rumina decollata (predatory snail), predaceous ground beetles, birds, snakes, toads, and other vertebrates
spider mites X X     X bigeyed bugs and minute pirate bugs, Feltiella spp. (predatory cecidomyiid fly larvae), sixspotted thrips, Stethorus picipes (spider mite destroyer lady beetle)
thrips X     X X minute pirate bugs, predatory thrips
weevils, root or soil-dwelling       X   Steinernema carpocapsae and Heterorhabditis bacteriophora (entomopathogenic nematodes)
whiteflies X X   X   bigeyed bugs and minute pirate bugs, Cales, Encarsia, and Eretmocerus spp. parasitic wasps, spiders

TIP: Only a few natural enemies (nematodes and convergent lady beetles) can be effectively bought and released. Lady beetles purchased through retail stores are unlikely to be sufficient in number and quality to provide control.

Ladybug, ladybug, fly away home...May your wish come true, and the pests in your garden are gone too!

Need more help identifying the friends and foes of your garden?

Email us at acmg@ucanr.edu. Or complete our help desk form our website.