June 24, 2018

Beneficial Bugs and Critters

What are beneficial bugs and critters?

Creatures that do a job for us, like killing pests, pollinating food plants, etc.

Why do we want them in the garden?

Without "beneficials", we have to do their jobs, spraying for pests, pollinating every peach blossom by hand, etc.  Unlike other methods of pest control, beneficials maintain a balanced ecosystem, do no contribute to environmental pollution or pesticide resistant pests, require little effort, and some of these bugs and critters are essential to our way of life.

Types of "beneficials"


Predators eat other insects.  There are too many to list, but here are a few common ones.  I left out several that I didn't have pictures of, like lacewings, and predatory wasps and flies.

Ladybugs eat aphids, mites, scale insects, mealybugs.

Praying mantis eat anything they can physically overpower, including other mantids.

Dragonflies/damselflies eat mosquitoes and other flying insects, and their
aquatic larvae eat mosquito larvae.

Many ground beetles are predatory and eat snails and slugs.

Fireflies are a type of ground beetle and their larvae eat snails and slugs.

Assassin bugs eat a variety of bugs, including ants, as you can see here.

Spiders -- I know, eww, for some people -- are beneficial.
They eat just about anything.  This "garden spider" is one
that I'm always happy to see.

Frogs and toads eat flies, roaches, grasshoppers, moths, and many other pests.

I love seeing lizards in my garden because I know they're eating pests.

Snakes are not everyone's favorite garden dweller, but they can be beneficial.
Larger snakes eat mammals, but many small snakes are harmless and have a
big appetite for insects.  Pictured is a rat snake.

Many types of birds, like this baby bluejays, eat bugs, like beetles,
grasshoppers, and caterpillars.

Many bats, like this tiny Mexican free-tailed bat, whom I lovingly
named Edward, eat mosquitoes by the thousands.

Austin is home to one of the largest urban bat colonies in the world.
A million and a half bats -- literally 1.5 million of them --
emerge from the Congress Avenue bridge in downtown Austin each night.
They eat between 5 and 10 TONS -- that's 10,000-20,000 lbs --
of insects nightly.  Read more about them here.


Parasitoid insects kill other insects by developing on or inside them.  Usually the female lays eggs in or on the host, then the eggs hatch and the hatched larvae eat the host -- sometimes from the inside out!
Braconid wasps are an example of a parasitoid wasp that doesn't sting humans.

Beneficial nematodes - I'm not sure how to categorize these, but they're technically a parasite, so I'm going to put them here.
Beneficial nematodes are a soil dwelling microscopic roundworm that uses biological warfare to kill soil dwelling insects, like fire ants and grubs.  The short version: they crawl into their host insect through any orifice they can find, and then they give the insects a bad case of food poisoning and eat them after they die.  You can read all the gory details here.

Decomposers or recyclers

Decomposers, also known as recyclers, break down waste, like dead plants and animals, releasing the essential nutrients back into the soil, water, and air.  These are critters that are likely to exist in a compost pile, although some are so small you would need a microscope to see them. 
Examples: earthworms, larval crane flies and and soldier flies, some nematodes, bacteria, protozoa, and fungi.


As a beekeeper, this group is dear to me.  Pollinators deliver pollen from one flower to another, which helps produce the food we eat.  Without pollinators, many common foods would not be available without a human pollinating each flower by hand.  Think about how expensive apples, peaches, pears, cherries, oranges, melons, zucchini, almonds, and even coffee would be, if humans had to do the work of millions of bees.
It's estimated that pollinators have a $20 BILLION impact on United States agriculture each year.

Some bats fall into the pollinator category, although I don't have any pictures of these bats. Bats pollinate many things, including cocoa and agave.  If you like chocolate or tequila, now you can have a new appreciation for bats.  You can read more about pollinating bats here.

Most experts say that honeybees are responsible for pollinating
approximately one-third of our food.

Solitary bees get very little credit compared to honeybees, but they
pollinate 80% of flowering plants worldwide. (source).
Here's an article I wrote about Solitary Bees.

Here's one of my many garden friends.

Butterflies, like this swallowtail, lay their eggs on a "host plant". 
The caterpillar hatches from the egg, eats the host plant and then
pupates and becomes a butterfly, repeating the cycle.

Most moths are also great pollinators, although not this luna moth.
Luna moths don't actually have mouths! 
You can read more about them on my Instagram.
Photo credit: my friend George Bohnsack

Hummingbirds are pollinators, but they also eat small bugs, like gnats.
Photo credit: my friend Rebecca Corbin

This little gal got stuck in the greenhouse at work.
She perked up after a drink and eventually flew away.

How to attract "beneficials"

Adopt an "integrated pest management" approach to gardening

  • Prevent and minimize the need for chemicals by keeping plants healthy
  • Plant disease/pest resistant varieties
  • Plant in the correct location
  • Use good watering practices
  • Ensure soil is healthy and drains well
  • Focusing on soil and plant health is the best prevention
    * Anytime you use a pesticide, even a natural one, spray it in the evening when most daytime pollinators, like honey bees and butterflies, are least likely to come into contact with it.

    You can read more about integrated pest management here on my blog.

Provide shelter

  • Leaf litter and ground cover plants
  • Overturned/partially buried pots
  • Compost pile
  • Bird houses
  • Keep flower beds mulched 2-3" deep with a wood based mulch and replenish 1-2 times per year.  Mulch provides shelter for beneficials, prevents weeks, reduces evaporative water loss, and insulates plant roots against heat and cold.  
  • Leave a well-drained, sunny portion of your flower bed free of mulch and vegetation for ground nesting solitary bees, and provide deadwood for deadwood nesting bees.
    You can learn more about solitary bees here on my blog.
  • Buy or build a beneficial bug house
  • Hang a bat house
Beneficial bug house I built for a workshop.

Provide water

  • A birdbath filled with water and marbles or stones provides a safe place for many types of pollinators to get a drink without drowning.
  • If you don't have a birdbath, you can do the same thing with a plant saucer on the ground.
  • Fountains

Provide food

  • Many beneficial critters eat nectar and pollen, but their diets vary greatly from species to species, so plant a variety of flowers that bloom in different seasons.  
  • Favorite pollinator plants are:
    • Carrot family: dill, parsley, fennel
    • Brassica family: sweet alyssum, stock, nasturtium, candytuft
    • Daisy family: sunflowers, coneflowers, mums, asters, yarrow, daisies, goldenrod
    • Mint family: salvia, basil, catnip, rosemary, thyme, lantana, agastache
  • Hang a hummingbird feeder
    • Make your own nectar with 1 part sugar to 4 parts water.  Keep it dye free.

Purchase beneficial insects

  • Most pollinators, like butterflies, bees, and hummingbirds are easy to attract if you plant their favorite flowers, but predators, like ladybugs, praying mantis, and beneficial nematodes are harder to attract specifically.  You can give your garden predator population a head start by purchasing them through a local nursery or online.

Additional sources

City of Austin's Grow Green Earth-Wise Guide to Beneficial Insects
Beneficials in the Garden, Types of Beneficials, Galveston County Master Gardeners
    Beneficials in the Garden, Attracting Beneficials, Galveston County Master Gardeners

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