Insects: Pest or Partner?

Ladybug on ragweed, chowing down on the aphids.

Finch Frolic Garden has been insecticide-free since it was first planted. It is a wildlife habitat as well as a food forest, and there are no chemicals at all used. Instead we rely on that habitat to create an integrated pest management system.

Western fence lizards are in and out of all of our veggie beds. We use no fertilizers other than compost, so they are safe.

The abundant frogs and lizards balance out most of the insect populations, and the birds, particularly bush tits and the other smaller gleaners, do their share.

A surprise visit from a skink! Welcome, little bug eater!

It may seem counter-intuitive to invite in and create habitat for insects when insects do the most damage.

A Baja California Treefrog, a.k.a. Pacific Chorus Frog (Pseudacris hypochondriaca hypochondriaca), clinging to the PVC pipe in the beet bed. He’s keeping the bugs in check while being cute.

But like humans, bugs are bug’s own worst enemy. Bring in the native insects!

Observation plays an enormous role in successful pest management; what better excuse for sitting in your garden looking at flowers?

Mexican Bush Katydid (Scudderia mexicana) on fennel.

For that is where you’ll see most of the beneficials.

A tiny jumping spider (family Salticidae) on yarrow. Spiders eat a lot of insects. The nectar draws in the bugs, and the spider waits.

In dryland areas everything is smaller: smaller tree canopies, smaller predators, smaller prey, and smaller insects. There are over 300 species of bee native to San Diego alone. None of them produce honey -there are no native honeybees to North America – but they are very important and very overlooked pollinators. Planting native plants, which have adapted over time to provide the best possible food sources in the most attractive packages, will be optimal for a native garden. Allowing non-natives that are also attractive to good bugs go to flower, along with the natives, is good too. For instance, dill, mint, basil, fennel and carrot all produce clusters of tiny flowers.

Blooming cilantro next to peas: both are good non-native small insect food sources.

Take a good squint at them and you’ll see very tiny creatures dining out on the pollen and nectar, and possibly each other. 

This scary-looking character (Chrysoperla rufilabris) is a wonderful friend, voraciously hunting many kinds of insects in adult, larval and eggs forms.

Lacewing larva are ugly ducklings that grow into lovely — and equally predatory — fairy-like adults.

Keeping a food supply for predatory insects is important to keep them in your garden. People buy ladybugs — most of which are non-native — and release them into a garden hoping they’ll linger and take care of any insect problem that might come up. Well, those poor bugs who survive packaging are hungry and thirsty. If there aren’t drops of water to sip on or aphids to munch right away, they have to go looking for them to survive. So leaving patches of plants with small infestations of aphids or other insects is important, as hard as that may be to do.

Recently while installing more raised pallet beds in the vegetable garden I was about to pull out a batch of ragweed.

Ragweed covered in aphids.

Its a native here, but an invasive one as it travels via underground runners and by seed. This batch was covered in aphids. Miranda, with her good eyesight, luckily stopped me. She saw dozens of ladybug larvae happily munching on all of those aphids.

Ragweed chock full of hungry ladybug larvae and hatched adults. They cleaned the plant of aphids and went to work on the rest of the garden.

There were adult ladybird beetles as well, but the number of larvae was incredible.

Nom!

The ragweed stayed. Eventually it was sprinkled with white aphid carcasses sucked dry by ladybug larvae. In a couple of weeks, the aphids were gone, the plant looked absolutely clean, and the ladybugs had had successful reproduction and had flown off to work in other areas of the garden and possibly in my neighbor’s yard. You are welcome. Then I pulled out the ragweed. We have plenty of it elsewhere for future ladybug mating sites.

Inspection of native plants at a friend’s house which were besieged by scale and aphids showed two things: one, that Argentine ants were farming insect on the leaves of the plant, and needed to be controlled, and that these plants also had the local rescue squad on hand. Thanks to Miranda again, she saw many types of native predatory insects feeding on the invaders.

hoverfly, beneficial insect, integrated pest management, Pseudodoros clavatus

Hoverflies or flower flies like this Four-spotted Aphid Fly (Pseudodoros clavatus) are not only our most common generalist pollinator, but also an important predator of plant-sucking insects such as aphids and thrips.

Larvae of Pseudodoros clavatus feasting on Oleander Aphids (Aphis nerii). Oleander Aphids are commonly found on milkweed.

We didn’t want to sprinkle food grade diatomaceous earth on the leaves or do anything to kill off the good guys, so we put borax ant bait in protected containers around the base of the plants and left them alone. The ants would die off and stop farming the bad guys, and the good guys would have great meals and be healthy and hardy enough to reproduce on site. The plants would recover and the natives would win.

Cryptolaemus montrouzieri, integrated pest management, beneficial

The worst gardening policy is the ‘squish first and ask questions later’ one. Although this long-haired cutie might look like the dastardly mealybug, it’s actually the larvae of the Mealybug Destroyer beetle (Cryptolaemus montrouzieri), a naturalized predator species that saved the California citrus industry once upon a time and which continues to covertly lend a hand in orchards and gardens every day.

Plants communicate in many different ways, and one of the ways is through scents that we cannot detect. These volatile organic compounds (VOCs) are released for various reasons and detected by surrounding plants. Native plants will release an alarm VOC when being attacked by insects that other natives pick up on, and they in turn release VOCs that attract the native predatory insects that will eat the pest. Having lots of native plants integrated in your landscape benefits your non-natives by calling in the rescue squad when the bad guys show up. Non-native plants, of course, release VOCs as well, but they are speaking a different language; their chemicals may not be recognized by the other plants, or they are signalling for beneficial insects that don’t live in the area. By providing good habitat – bird boxes, sources of water for birds, lizards, frogs, toads and insects, having mulches and native bee nesting boxes around the property, allowing some plants to flower, and of course, not using insecticide, you’ll have a balanced ecosystem full of wildlife in no time.

bird, integrated pest management, orange-crowned warbler

Industrious Orange-crowned Warblers (Oreothlypis celata) can be seen poking through bushes, trees and even tall lush grass prowling for small insect prey.

Remember that even if a product is from plant sources – such as neem oil or pyrethrum, doesn’t mean that it isn’t powerful. No insecticide will kill the target species and leave all the good guys alone. Scorched earth policy is never the best way to go in nature. Sprinkling food grade diatomaceous earth just where the bad bugs are and not liberally spreading it around, or using a soap and water spray on infested leaves, can help. Just look first and see if there are signs of beneficials already there working for you. 

beneficial, integrated pest management, Bracon celer

This female braconiid wasp’s tail-like long, thin ovipositor is a weapon of population regulation. She uses it to inject her eggs into the bodies of her prey — fruit flies in this species — and her maggots eat their hosts from the inside.

Remember too that if you purchase plants that have been treated with insecticide, particularly those with systemic insecticides (which means they work internally throughout the plant), they will kill anything that takes a bit out of them. The poison goes through the pollen and nectar as well. So birds nibbling the leaves, pollinators and beneficial predatory insects having a meal, butterfly caterpillars, and the insects that eat all of the above, will all be poisoned. If that milkweed you bought to feed the Monarchs don’t have aphids on them, be suspicious. Those tags at the big box stores that say the plants have been treated with insecticide – neonicotinoids – that are safe, are excluding facts about what else they effect. Systemics stay in the plant, possibly for the life of the plant. They don’t go away. GMO seeds have had their DNA modified to accept the use of chemicals, both herbicides and insecticides. Glysophate, a derivative of Agent Orange, is now found in mother’s milk, in human and animal tissue, and in most soil. We have to stop using chemicals for the health of ourselves and our ecosystem. So buy plants and seeds from sources you can trust. Just because the big box stores offer a good return policy doesn’t validate their products. You are buying inferior plants that are toxic to beneficial insects. That bug-free milkweed plant will kill the Monarch caterpillars feeding on it. The more you demand and support chemical-free plants, the more suppliers there will be. On my Resources page under Shopping I have listed many wonderful sources for plants and seeds online, but look locally first.

minute pirate bug, integrated pest management

A minute pirate bug (Orius tristicolor) scans the deck of this native Dove Weed (Croton setigerus) leaf for any of the mites, thrips, aphids and caterpillars it makes its vittles from. No prey, no pay, and dead bugs tell no tales about this tiny but deadly predator!

Get to know your native insects. Have a seat by the flowers and take a good look – with a magnifying glass if necessary – and be amazed at the hundreds of little workers you didn’t even know that you had.

 

2 thoughts on “Insects: Pest or Partner?

  1. Thanks so much Karl. No matter how much we already know, observation brings us more surprises every day. Miranda is an I.D. fanatic and learning about the roles each of these tiny insects play is amazing. Thanks for commenting. Diane

  2. Awesome article, Diane. I sometimes can’t help myself from correcting errors in these types of Insect Op-Ed’s. But in this case, it all checks out. You two are doing great work learning new things about eco agriculture and teaching it to others!

Leave a Reply

Your email address will not be published. Required fields are marked *