Chapter 52 Recognize Your Allies

Many more insects are beneficial (or at least neutral) than insects that are pests. One of the fundamental goals of IPM is to encourage more beneficial predators in your growing space that will help keep the pests in check.

These are the most common beneficial species in this area that you want to encourage. For each species I have list their main prey, plants or conditions that attract them, and other bits of useful information. Sources to buy them online and scientific names of all host plants are at the end of the article.

52.1 Old Friends

These are the species that we think of most often as beneficial insects. Both ladybugs and mantis egg cases are available to order online.

52.1.1 Ladybugs

Ladybugs can consume more than 5,000 aphids during their lifetime. Both the immature larvae and adults feed on them. They prey mainly on aphids but will switch to whiteflies, mites, fleas, and even Colorado potato beetle when these prey are abundant. They are attracted by several wildflowers and herbs including fern-leaf yarrow, common yarrow, bugleweed, dill, golden marguerite, butterfly weed, coriander, Queen Anne’s lace, fennel, prairie sunflower, penstemon, cinquefoil, marigold, tansy, dandelion, speedwell, and hairy vetch.

Ladybugs are available in large quantities commercially for release at home. They are finicky about habitat, so follow the instructions carefully when releasing them. Otherwise they will fly off almost immediately.

52.1.2 Praying Mantis

Carolina mantis (Stagmomantis carolina) adult (1) and juveniles (2) emerging from an egg case in spring. Link to original image 1; link to original image 2.

Mantids are aggressive hunters. Large females may even try to ambush hummingbirds. They eat a wide range of prey including caterpillars, moths, beetles, and crickets. They are attracted by tall grasses and shrubs, cosmos, marigolds, and dill.

To get them started locally, look for the brown egg cases in late winter on dried tall grasses in weedy areas, or stands of dead goldenrod. Break off the stem to which the mass is attached, and use string to tie the egg case in a protected spot near your trees. The nymphs emerge in mid-Spring.

52.1.3 Spiders

Spiders. 1. Orb weaver spider (Argiope aurantia). 2. Wolf spider (Tigrosa georgicola). 3, 4. Jumping spiders (Phidippus audax, Phidippus otiosus). Link to originals: image 1; image 2; image 3; image 4.

Many people are afraid of larger spiders, but even the tiny jumping spiders are beneficial. They hunt aphids, roaches, grasshoppers, mosquitoes, and fungus flies. Tall plants attract weaving spiders, while mulch attracts wolf spiders.

52.2 Unexpected Friends

These are beneficial predators that you likely have encountered in the past but might not have realized it.

52.2.1 Lacewings

Green ((1) and brown (2) adult lacewing. Link to originals: image 1; image 2.

Green and brown lacewings (Chrysopa spp., Micromus spp.) are inch-long dainty insects that show up on wildflowers starting in late spring. These clumsy fliers may not look like much, but looks are deceiving. Lacewings (also called aphid lions) may be the most aggressive predators you ever encounter. The larvae gorge on soft-bodied insects like aphids, whiteflies, leafhopper, mealybugs, and small caterpillars of pest moths. When one prey item is gone they switch to another.

Lacewings. 1. Eggs. 2,3. Green and brown lacewing larvae. Link to original image 1; link to original image 2; link to original image 3

Adults feed on pollen and nectar from yarrow, dill, angelica, four-wing saltbush, prairie sunflower, coriander, and dandelion. If these food sources do not attract the adults, you also can buy lacewing eggs from commercial suppliers.

Lacewings eggs are attached to long stalks to keep the larvae from eating each other. They feed until they have enough energy for metamorphosis, then pupate. Adults emerge and repeat the cycle. Unlike ladybugs, lacewings stay in one area once they get established, coming back each year.

52.2.2 Wheel Bugs, Leaf-footed Bugs, and Assassin Bugs

One of several local species of wheel bugs (1), and a leaf-footed bug (2). Link to original image 1; link to original image 2.

Wheel, leaf-footed, and assassin bugs are true bugs (Order Hemiptera), meaning they have piercing, sucking mouthparts. Ironically, aphids are one of their close relatives in this group. In the photo of the wheel bug above, you can see its large sucking beak folded under its narrow head. Both the nymphs and adult bugs are generalists that feed on a variety of insects including aphids, caterpillars, bugs, beetles, and more. They use their stout beak to inject prey with a toxin and enzyme that kills it within 30 seconds, then they suck out its liquified body fluids. They do bite painfully if handled, but the bite is not dangerous to humans.

Wheel bug eggs and nymphs. Link to original image.

Recently hatched broods tend to stay close together. Be careful not to mistake a group of them for pests. I have seen both juveniles and adults strongly attracted to mint and thistle flowers.

52.2.3 Wasps and Hornets

Wasps and hornets hunt and kill tent and other pest caterpillars then feed them to their brood back in the nest. A large hornet nest can have hundreds of individuals, each hunting to feed itself and the next generation. They can greatly reduce your local population of pest caterpillars.

Many people are more afraid of wasps and hornets than they should be. I learned this a few years ago when I spent the summer watching bald-faced hornets build their gray football-shaped paper nest. It was not high in a tree, but tucked under a rose shrub just 3 feet off the ground, on the wall of my garden shed. We spent the entire summer peacefully; I avoided lingering near the nest, but walked within 5 feet of it several times a day on weekends. The only time the hornets ever showed any aggression was when I tried to set up a camera tripod less than 3 feet away from the nest. I backed off, and so did they.

Most wasps and hornets are only aggressive when defending their nests or handled roughly. So if the nest is not in a place where someone is likely to hit it accidentally, leave it alone. (Obviously if you or a family member is allergic to bee stings, it is best to remove the nests.) If one lands on you, calmly brush it off and walk away. If they do not sense a threat, wasps and hornets are less likely to sting.

It may sound slightly hypocritical, but my patience does not extend to yellow jackets. They defend their in-ground nest much more aggressively. Also, they feed more on sugary foods than on other insects.

52.2.4 Ground Beetles, Caterpillar Hunters, and Soldier Beetles

These beetles from the Carabidae family eat a wide range of soft-bodied prey, including slugs, caterpillars, ants, Colorado potato beetles, cutworms, grasshopper eggs, and aphids. Plants that attract them include evening primrose, amaranthus, clover, goldenrod, zinnia, and marigold.

Black Caterpillar Hunter (Calosoma sayi). Link to original image.

Vivid Metallic Ground Beetle (Chlaenius spp.) Link to original image.

Fiery Searcher Caterpillar Hunter (Calosoma scrutator). Link to original image.

Scarites Ground Beetle (Scarites spp.) Link to original image.

Soldier Beetle (Chauliognathus spp.) Link to original image.

Ground beetles are typically only active at night. True to their name, they spend most of their time on the ground or hunting in ground debris. Soldier beetles are more likely to be seen in daytime. While they are commonly seen on plants, soldier beetles do not damage plants and are harmless to people.

52.3 New Friends

These are predatory insects that you may not have encountered before.

52.3.1 Minute Pirate Bugs

Pirate bugs (Orius sp.) are common but hard to spot. They are small (2-3mm long), somewhat oval-shaped, and black with white wing patches. The wings extend beyond the the tip of the body. Nymphs are small, yellow-orange to brown, and fast moving. Both nymphs and adults prey on soft bodied insects like spider mites and thrips (their two favorites), plus aphids, and small caterpillars and their eggs.

Minute pirate bug next to a leaf vein (1), and close up (2). Link to original image 1; link to original image 2.

Minute pirate bugs favor areas with spring and summer flowering shrubs and weeds because they feed on pollen and plant juices when prey are not available. They especially like caraway, cosmos, fennel, alfalfa, spearmint, goldenrod, and yellow marigolds.

Adults consume over 30 spider mites in a day, and will kill more than they eat. They use a long beak to stab prey and suck them dry. Occasionally they bite humans, but the bite is not venomous or harmful.

They are sensitive to insecticides like pyrethroids, organophosphates, and carbamates. Providing and not spraying refuge food plants helps keep them onsite and working to limit pests.

52.3.2 Syrphid Flies

A hover fly adult (1), and larvae (2). Link to original image 1; link to original image 2.

Syrphid or hover flies often are mistaken for wasps or bees, which they imitate to ward off attack. Hoverfly larvae feed on pests, while the adult flies feed on pollen. They are attracted by fern-leaf and common yarrows, bugleweed, flowering allium, basket of gold, dill, golden marguerite, dwarf alpine aster, masterwort, saltbush, poppy mallow, caraway, feverfew, coriander, cosmos, Queen Anne’s lace, fennel, English lavender, poached egg plant, statice, butter and eggs, lobelia, alyssum, lemon balm, pennyroyal, spearmint, bergamot, penstemon, parsley, cinquefoil, gloriosa daisy, stonecrops, goldenrod, betony, marigold, crimson thyme, speedwell, and zinnias.

52.3.3 Predatory Stink Bugs

Every winter, homes and offices around here are invaded by brown stink bugs coming in from the cold. These and most other stink bugs are just a nuisance or minor pests at worst. However there are two types of beneficial predatory stinkbugs.

Spined soldier bug (1); a feeding bug (2). Link to original image 1; link to original image 2.

Spined soldier bugs (Podisus maculiventris) feed on grubs, caterpillars and soft-bodied insect pests. Spined soldier bugs are easy to tell from common stink bugs by the thorn-like points on the “shoulders” of their shield-like back. Colors range from brown to yellow and speckled with black spots.

Our newly arrived predatory stink bugs. Image 1 is an adult, Image 2 shows the nymphs. Link to original image 1; link to original image 2.

The second beneficial only appeared in central North Carolina in the last decade or so. They are very hard to miss: glossy black with brilliant orange to blood red spots. This predatory stink bug (Euthyrhynchus floridanus) is normally found much further south, but I’ve seen individual adults and clusters of nymphs several times here locally over the last few years. Most of its prey consists of larger plant-damaging bugs, beetles, and caterpillars. If you see these colorful newcomers, leave them be; they are working in your favor.

52.3.4 Predatory Mites

Predatory mites. 1. Magnified image of a predatory mite killing a spider mite. 2. Close-up of Amblyseius sp. Coloris not a good indicator of predatory mites; there are several spider mites that also are bright red. Similarly, there are both pest and beneficial species of two-spotted spider mites. Link to original image 1; link to original image 2.

Spider mites are near-microscopic pests related to spiders. They attack most tree species, but are a particular problem for conifers. Tiny irregular webs are a sure sign of a spider mite infestation. They feed like aphids, punching tiny holes in the leaves or needles. Each spot where they feed turns white or pale, leaving the foliage mottled. In addition to damaging foliage, spider mites transmit a variety of plant viruses.

Spider mites are notoriously hard to kill. Introducing their natural predators is one of the most consistently effective control methods. Different species are more or less effective depending on the temperature and humidity. Some only do well in greenhouse conditions, while others are better suited for outdoor use. The table below summarizes the best conditions for several commercially popular species.

Name of species	Preferred Temp., Humidity	Main Uses	Notes
Amblyseius andersoni	Hatches 68-77°F; feeds at 42-100°F; higher humidity needed at higher temperatures	Good for pre-emergent control	Native to N. America. They will also feed on thrips, pollen and honeydew; however, they will not control a thrips infestation.
Amblyseius swirskii	Hatches >77°F; feeds >60°F; prefers warm environments w/RH>70%	Controls thrips, whitefly along with mites	Adults can survive by consuming pollen, mold.
Galendromus occidentalis	Feeds 80° to 110°F; prefers 30-60% RH	Ideal for outdoor use on trees	Adults are more active than prey. Will switch to pollen when prey is unavailable.
Neoseiulus (Amblyseius) californicus	50-105°F, 40-60% RH	Slow feeder, so effective against low mite populations	Well suited to outdoors in southeastern US. Can feed on pollen. Reproduces biweekly.
Neoseiulus(Amblyseius) fallacis	>64°F, >50% RH	Good performance in orchards	Reproduces faster than other species. Voracious feeders.
Phytoseiulus persimilis	68-90°F, 60-90% RH	Spider mite specialists. Best as pre-emergent to prevent infestation; poor control post-infestation	Tend to leave plants when prey numbers are too low.

52.3.5 Trichogramma Wasps

Trichogramma wasp on caterpillar eggs. Link to original image 1.

Trichogrammas (Trichogramma spp.) are TINY (~1mm) stingless parasitic wasps that look like miniature fruit flies. They kill more than 200 undesirable pest caterpillars including armyworm, bagworm, borer worms, cutworm, and others. The females lay their own eggs inside the eggs of caterpillars. The larvae develop inside, feeding on the host’s egg and killing them before they can hatch on start feeding on trees.

Even if you have a large healthy population of Trichogramma, do not expect to see them often. Both eggs and larvae live inside of caterpillar eggs, and the adults are too small to see easily.

Many organic gardening suppliers sell Trichogramma that you can release to jump-start local populations. Garden plants that attract and keep them in your garden or growing area include: yarrow, flowering allium, marguerite, dill, masterwort, purple mallow, caraway, coriander, cosmos, Queen Anne’s lace, fennel, statice, butter and eggs, lobelia, sweet alyssum, lemon balm, pennyroyal, parsley, cinquefoil, stonecrop, marigold, tansy, crimson thyme, zinnia.

They are sensitive to broad spectrum insecticides; avoid spraying these chemicals if possible, and don’t spray host plants.

52.3.6 Damsel Bugs

A typical damsel bug. Link to original image.

Damsel bugs are members of the insect family Nabidae, which has 23 different genera. They are generalist predators that eat caterpillars, mites, aphids, and potato beetles. For all practical purposes, they fulfill the same function as assassin and wheel bugs.

Damsel bug populations can thrive if you provide them alternative places to hide. They are attracted to caraway, white cosmos, fennel, goldenrod, spearmint, alfalfa, and yellow marigolds.

52.4 Feeding Your Friends

Pollen- and nectar-rich plants attract a variety of beneficial insects that prey on pests. Many plants in the Aster family (Asteraceae) and carrot family (Apiaceae) are especially good forage plants, providing nectar, pollen, and resting places.

These are the species named in one or more of the earlier entries. Try growing several of these species in pots and placing the pots in and around your trees.

Common Name	Scientific Name	Common Name	Scientific Name
Fern-leaf yarrow	Achillea filipendulina	Statice	Limonium latifolium
Common yarrow	Achillea millefolium	Butter and eggs	Linaria vulgaris
Summer beauty, lavender globe lily	Allium tanguticum	Lobelia	Lobelia erinus
Carpet bugleweed	Ajuga reptans	Sweet alyssym	Lobularia maritima
Basket of gold	Alyssum saxatilis	Alfalfa	Medicago sativa
Angelica	Angelica gigas	Lemon balm	Melissa officinalis
Golden marguerite	Anthemis tinctoria	Pennyroyal	Mentha pulegium
Dill	Anethum graveolens	Spearmint	Mentha spicata
Milkweed	Asclepias spp.	Wild bergamot	Monarda ﬁstulosa
Dwarf alpine aster	Aster alpinus	Rocky Mt. penstemon	Penstemon strictus
Masterwort	Astrantia major	Parsley	Petroselinjum crispum
Four-wing saltbush	Atriplex canescens	Cinquefoil	Potentilla recta ssp. ‘warrenii’ and Potentilla villosa
Borage	Borago officinalis	Mountain mints	Pycnanthemum spp.
Calendula, pot marigold	Calendula officinalis	Roses	Rosa arkansana, R. canina, R. carolina, R. multiflora, R. nitida, R. palustris, R. rubiginosa, R. rugosa (these are more fragrant cultivars)
Purple poppy mallow	Callirhoe involucrata	Gloriosa daisy	Rudbeckia fulgida
Caraway	Carum carvi	Black-eyed Susan	Rudbeckia hirta
Feverfew	Chrysanthemum parthenium	Stonecrop	Sedum kamtschaticum, S. spurium
Coriander	Coriandrum sativum	Goldenrod	Solidago virgaurea
Cosmos	Cosmos bipinnatus	Wood betony	Stachys ofﬁcinalis
Cardoon	Cynara cardunculus (especially attractive to assassin bugs and predatory wasps)	Marigold	Tagetes tennuifolia
Queen Anne’s lace	Daucus carota	Tansy	Tanacetum vulgare
Echinacea	Echinacea purpurea	Dandelion	Taraxacum officinale
California buckwheat	Eriogonum fasciculatum	Crimsom thyme	Thymus serpylum
Fennel	Foeniculum vulgare	Nasturtium	Tropaeolum majus
Sunflower	Helianthus annuus	Spike speedwell	Veronica spicata
Prairie sunﬂower	Helianthus maximilianii	Hairy vetch	Vicia villosa
English lavender	Lavandula angustifolia	Zinnia	Zinnia spp.
Poached egg plant	Limnanthes douglasii

52.5 Bringing In Fresh Troops

Forage plants and cover are important for keeping beneficial insects around, but what if you do not have them around to start with? There are several companies that specialize in producing and selling beneficial insects to gardeners and nurseries. These are vendors that have good reputations and carry a range of generalist and specialist predators.

ARBICO Organics. One of the largest suppliers currently selling to home users. Source for ladybugs, lacewings, assassin bugs, predatory mites, mantids, minute pirate bugs, and Trichogramma.
A.M. Leonard. Source for ladybugs, Trichogramma, predatory mites, lacewings.
Beneficial Insectary. Lacewings, Trichogramma, thrips predators, aphid parasites, spider mite predators, minute pirate bugs, damsel bugs.
Biocontrol Network. Another of the sources with whom I have done business.