• By Cleve Campbell
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  • April 2015 - Vol 1. No. 4

My wife recently commented that we could get help in the garden by planting an insectary.  Insectary?  Now that was a head scratcher.  Naturally, I received the eyes rolling in the head look, when I meekly asked, “What’s an insectary and why do we need one?”  Now, I thought we were looking for help, but usually when I heard that dreaded phase, ” We need to…” that’s usually  code for  “you need to…” in short, work.  Now what?   After a moment of silence and a deep breath, my bride informed me that one form of an insectary is a type of garden or grouping of plants (insectary plants) that attracts and hosts bugs.  Naturally I uttered a few inaudible words — “WHAT?  ATTRACT BUGS!  Have you lost your mind or what?”

Problem?   What problem?  Piece of cake —  this insectary thing wasn’t going to be a problem because I knew I was about to wake up from some sort of weird dream and this insectary thing would just go away.  You guessed right; no such luck.  “We” are going to have an insectary.

The more I thought about this upcoming insectary project, the more puzzled I became, because at our house we often refer to the vegetable garden as “The War Zone — whether it’s fighting the critters, the weather, too hot, too cold, too much rain, too little rain, fighting weeds, cold soil resulting in poor seed germination and that endless war on bugs.  There comes a time when a fellow has to draw a line in the sand.   Now with this attracting bug project, the moment for line-drawing may have arrived.  Having not been on a good roll recently, I figured I needed to do a little insectary research before I made some profound political statement, resulting in another of my frequent trips to the doghouse.

Naturally over the years, I had observed various activities of bugs in the yard and garden.   I have been bitten more than a few times by bugs dining on my blood, seen the holes eaten in green bean plants, eggplants and potato leaves by plant-eating bugs, observed small bee-like insects hovering around dill flowers, and delighted at the sight of a praying mantis stalking a bug on an asparagus fern.  I have squashed more than a few unsuspecting bugs and egg masses between my thumb and forefinger on my daily patrols though the vegetable garden. Many of my gardening friends, myself included, share a similar perspective on bugs: there are two types of bugs,  live ones and dead ones, and the only good one is a dead one. And now with this insectary project we want to attract bugs.  Amazing!

After spending a little time scratching my head, I went to the computer to do a little research on this insectary thing.  Well, I was right about one thing; there are two (2) major categories of bugs: pests, the bad guys, and beneficial bugs, the good guys.  And to my amazement,  less than 1 percent of all insects are considered pests; however, an estimated one-fifth of the world’s crops are destroyed by plant-eating or herbivorous insects. Remembering last season’s  bug-eaten cabbage, bean and eggplant leaves in my garden, it’s obvious that my vegetable garden is doing more that its fair share to support the herbivorous insect population.

So doing the math, the remaining 99 percent of the insects are beneficial or considered neutral.  The beneficial insects consist of three (3) kinds: predators, parasitoids and pollinators, a.k.a the 3 P’s.

Predators eat other insects.  Examples of predators include the Lady beetle (Hippodamia convergens), Assassin bug (Redruviidaye), Damsel Bug (Nabidae), Big-eyed bug (Lygaeidae) and Green lacewing larvae. Parasitoids are insects that lay eggs in or on other insects, resulting in the death of the host insect. Examples of parasitoids include the many wasps such as the Thichogramma wasp (Trichogrammatidae).  Without pollinators, fruit, vegetables and the production of seeds would be greatly reduced.  The best known pollinator is the honeybee, but our gardens also benefit from other native pollinators such as bumblebees and mason bees.  In addition, adult parasitic insects such as small wasps feed on pollen and nectar and are also considered to be pollinators.

After pondering this good bug, bad bug revelation, I was stumped, it just didn’t make sense.  If the general population of bad bugs is less than one percent, why aren’t the good guys winning the war in my garden?  Why are there holes in my bean and eggplant leaves?  After doing a little more research, I discovered that Mr. Darwin’s concept of the survival of the fittest is still alive and well. Not only is it a war; it’s an arms race. Unfortunately, the battlefield may have shifted in favor of the bad guys.  In the 1940s the first modern synthetic insecticide, dichloro-diphenyl-trihorethane was introduced; you may have heard of this insecticide; some folks refer to it as DDT.

DDT poster

DDT Poster: Source USDA

Arms race?  This is a very simplistic term for a very complex problem that developed over the past 70-80 years. DDT was hailed as a miracle. In fact,  the developer, Paul Muller, received the Nobel Prize in 1938 for discovering the insecticide qualities of DDT.  Shortly after World War II, DDT was adopted as the insecticide of choice for controlling pests on agricultural crops.

Now for the bad news.  Shortly after DDT was introduced as an insecticide, a housefly in Sweden was discovered to be resistant to DDT. Farmers begin observing that DDT was becoming less effective for controlling pests; naturally the solution was “if some is good; more is better.”  Not only was the insecticide concentration increased, but the frequency of treatment was also increased, and the more DDT that was applied to crops, the less effect it had on the pest population.

What happened is that not all the insects were killed with the first application of DDT, so the survivors were genetically predisposed to be resistant to the insecticide and able to survive. Repeated applications and higher concentrations had little effect; the insecticide resistant insects continued to survive. So after a number of life cycles, the majority of the pest population was unaffected by the insecticide. So how long does it take to develop a population of resistant insects? In some cases not long, because of the rapid reproductive rate of many insects. In some pests, a life cycle can  take place in several weeks, meaning a number of generations can be produced in a single season or year.

So it becomes easy to see that repeated applications of an insecticide will eliminate all the non-resistant pests in the population, leaving only the resistant pests to survive. In a short period of time the entire population of insects will be resistant. Remember Darwin and his theory of  survival of the fittest!  (DDT was banned in this county in 1972 because of environmental threats to wildlife and potential human health issues.) Once we have resistant pest population the arms race begins, and the only solution is to develop new and improve insecticides, which only initiates the cycle again. This insecticide cycle is often referred to as the ” pesticide treadmill”  — once it starts, it repeats over and over and it is difficult to get off.  It is estimated that more than 500 anthropoid species worldwide have developed a resistance to insecticides. (Note: the term Pesticides includes herbicides for destroying unwanted plants (weeds); insecticides for controlling insects; fungicides for controlling molds, mildews, and fungi and compounds to control small animals such as rats and mice).

Okay, what happens to the beneficial insect population when  broad nonselective insecticides are applied? Well, they are killed by the insecticides, and unlike the targeted pests, in most cases, they are not as adaptive in developing resistance to the pesticides so their population decreases.  It should be noted that available  research and documentation  on the effect of insecticides on beneficial insects appears to be very limited.  Most of the research available is focused on how effective the insecticide is on the pest population.

Now I must admit, this revelation of resistant pests or super bugs is getting a bit scary and my bride’s suggestion of an insectary may not be half bad!

After a little web surfing, it looks like this insectary project is going to be a breeze, it’s just a matter of hitting the seed catalogs, looking at the pictures of the pretty flowers and ordering a few flower seeds and then, the old plant-it-and-they-will-come strategy. Then I heard that familiar voice: “Not so fast buster, just like the vegetable garden, we need to do a little planning.  This is not going to be a ‘Chocolate Box Ecology‘ project.” I think that chocolate box was in reference to Forest Gump — where the line went something like “Life is like a box of chocolates; you never know what you are going to get.”  For what’s it’s worth, I wasn’t about to challenge her strategy or ask for more infomation regarding her metaphoric statement.

It must have been a vision.  I had this flash back to a book titled The Art of War written in the 6th century by a Chinese author, Sun Tzu. According to Mr. ,Tzu it is imperative to know your enemy before entering battle. And since my garden was a war zone, I need to identify and get to know the enemy. After pondering this revelation for a short period, I came up with a very simple four-pronged war plan:

  1. Identify the bad insects, the pests
  2. Identify the good insects, the guys that eat the bad guys.
  3. Identify the Insectary plants that attract and host the good guys.
  4. Select and plant insectary plants in and around the vegetable.

To successfully attract beneficial insects, a little planning is required.  Plants need to be selected so there is secession of flower blooms throughout the growing season. Flowers provide a food source — pollen and nectar —  to many beneficial insects; they do not dine only on aphid filets.

Below is my starter list of beneficial insects, their prey and plants that they like:

Beneficial Pests Plants
Lacewings Aphids Cilantro, Cosmos, Dill, Fennel, Queens Anne’s Lace,
Tansy and Yarrow
Lady bugs Aphids Buckwheat, butterfly weed, Cilantro, Dill, fennel
Marigold, Queen Anne’s Lace, Veronica Yarrow
Hover Flies Aphids Alyssum, Cilantro, Cosmos, Buckwheat,
Mealybugs Lemon Balm, Parsley, Marigold, Thyme, Zinnia
Parasite Wasps Moths, Yarrow, Dill, Cilantro, Cosmos, Queen Anne’s Lace,
White Flies Lace Lemon Balm, Parsley, Sedum Marigold,
Thyme, Zinnia
Tachinid Flies Cabbage Lopper Buckwheat, Lemon Balm, Parsley
Cut Worms,
Squash Bug

This is only a very brief starter list.   More comprehensive lists that include native plants and “garden” plants may be found at, Virginia Native Plant Society Plant Lists, VCE Publication: ENTO-52 and The size of an insectary may vary anywhere from a few insectary plants in flower pots to acres of insectary plants.

The VCE Publication: ENTO-52 suggested that buckwheat may be the ultimate insectary plant because it is insect-friendly by providing abundant and accessible nectar over a long bloom time; in addition, it suppresses weed growth, and several crops may be planted over the growing season. I will plant buckwheat in that empty space between the potato rows this year.

It’s all about diversity, and the long range plan is that I need to build a layered buffet that provides constant blooms throughout the season, including ground covers, annuals, perennial flowers, native grasses, ground covers and trees. Native plants such as butterfly weed, Joe Pye weed, asters, wild bergamot, Virginia mountain mint and New England aster will be featured; however, non-natives such as zinnia, buckwheat, sunflowers and herbs will also be included because they are also effective in attracting beneficial insects. An insectary garden is a form of companion planting based on the attributes plants can share in deterring pests, acquiring nutrients and attracting natural predators, with the added bonus of adding decorative elements to vegetable garden and a bounty of cut flowers for the dinner table.   It’s all starting to make sense.

Now the hard part: an insectary garden takes patience.  A colony of aphids, cutworms, or squash bugs may appear overnight, but it takes time to build up an army of beneficial insects, and that just doesn’t happen in a flash. It has to start early in the gardening season. The results are not instantaneous but the benefits in the garden are cumulative over time. As the plantings mature and resident populations of beneficial insects become established, the need for chemical pesticides and other aggressive insect control techniques will diminish. Perhaps the most difficult challenge is to identify the pest problem before I react, and resist the urge to spay or dust insecticides. Now when I go on patrol in the vegetable garden, I will go armed with a hand lens and insect reference book. Before I squash that bug between my forefinger and thumb or that egg mass attached to a leaf, I want to know if it is a foe or friend. And this is not as easy as it sounds. There are several bad insects that are very similar to beneficial insects. Two that come to mind are the Mexican bean beetle (bad) and the Ladybug (good) and the brown marmorated stink bug (bad) and the assassin bug (good).

Mexician Bean Beetle Photo Credit: Stephen Ausmus, USDA, ARS, AFRS

Mexican Bean Beetle Photo Credit: Stephen Ausmus, USDA, ARS,

Lady Beetle Photo Credit: Scott Brown, USDA, ARS, AFRS

Lady Beetle
Photo Credit: Scott Brown, USDA, ARS, AFRS







BMSB and Spined-Soldier Bug  Photo Credit: Brent Short , USDA, ARS, AFRS

BMSB and Spined-Soldier Bug Photo Credit: Brent Short , USDA, ARS, AFRS

Now I’m not sure about going totally insecticide-free. However, I want to give my beneficial army a fighting chance, I now know that beneficial insects are susceptible to insecticides, so the plan is to avoid all those non-selective ones, you know, the ones that claim to control over 200 types of insects. So I will be very selective on the insecticides I choose to use. Once I identify the pest problem, I will avoid those non-specific insecticides. Once it appears my beneficial warriors can’t keep up with the villains, I may look at a select few organic products like neem, spinosad, BT. horticultural oil, insecticidal soap, since these products break down quickly and are less damaging to beneficial insects. And just like the bad stuff, read the labels, follow the instructions and comply; because the label is the law.

Now don’t tell the wife, but I think she may be onto something with this Insectary Garden and I am sure looking forward to the help arriving.


Ellia, Barbara  W., Bradley Fern M., “The Organic Gardner’s Handbook of Natural Insect And Disease Control,”  1996.”

“Beneficial Insects In the Home Garden,” Dick Post, Horticulture Specialist, University of Nevada.

“DDT – A Brief History and Status”, EPA- United States Protection Agency.                                                      

“Why Natives?” Virginia Native Plant Society,

“Jumping off the Pesticide Treadmill”, Purdue University,

“Farmscaping, Making use of Nature’s Pest Management Services”,  Clemson University,

“Improving Pest Management with Farmscaping,” VCE Publication ENTO-52NP (ENTO-52NP).

“Plants That Attract Beneficial Insects’, The Permaculture Research Institute.

“Integrated Pest Management Ideas For Vegetable Gardens,” VCE Publication 426-708.

“How Pesticide Resistance Develops” Michigan State University.

“Beyond the Birds and Bees’, The Xerces Society for Invertebrate Conservation.

“For the Birds,Butterflies & Hummingbirds-Creating Inviting Habitats”‘ VCE Publication HORT-59 NP.

“Pollinator Plants-Mid-Atlantic Region”,The Xerces Society for Invertebrate Conservation.