Computerized Biological Control

Garden Insects: What They Eat and What Eats Them

EXPLORE hundreds of garden insects (and the like).

DISCOVER biology and non-chemical controls, identification of groups and species, hundreds of plants with lists of pests, benefits and damages indexes (with first aid), and beneficial organisms for sale (cross-referenced with suppliers).

ENRICH your garden (or undergraduate courses in ecology, entomology, and horticulture).



© 1992 – 1998 Douglas Drenkow. All Rights Reserved.

Introduction to Computerized Biological Control

Thank you for your interest in “Bug” Doug’s Computerized Biological Control! I’m “Bug” Doug Drenkow, an organic vegetable gardener for many years. In 1980 I received my Bachelor of Science degree with Highest Honors in Plant Science, from the University of California at Davis. For years now I’ve been researching (in addition to a great many other subjects) alternatives to pesticides for the control of insect pests. I’ve put my insect-control research on computer disks for three reasons.

First, because there are tens of millions of us gardeners nationwide and there are home computers in a quarter of all households, there are millions of potential users of Computerized Biological Control.

Second, because insects are the most numerous and diverse group of animals on Earth, I have accumulated thousands of pages of research, “crying out” for a medium as compact as computer disks.

Finally, because insects have so very many complex ecological interrelationships — each species feeding on and, in turn, being fed on by a wide variety of other organisms — relationships that are the key to biological control, abundant cross references are vital: With this “user friendly” program and comprehensive data base, each of these thousands of pieces of useful and fascinating information is literally at our fingertips!

I trust that you will have never found another reference on garden insects that is as thorough — especially ecologically — and yet as simplified and well organized as Computerized Biological Control. It will help you enrich your garden ecosystem and answer those ever-popular insect questions: “What is it?” and “What does it do?”

Back to Top

Major References

Borror, Donald J., Dwight M. DeLong, and Charles A. Triplehorn, An Introduction to the Study of Insects, 4th and 5th editions, Saunders College Publishing, San Francisco, 1976 and 1981.

Borror, Donald J., and Richard E. White, A Field Guide to the Insects of America North of Mexico, The National Audubon Society’s Peterson Field Guide Series, Houghton Mifflin Company, Boston, 1970.

Drenkow, Douglas, Food Webs of Insects and Their Kin, DED Electronic Publishing, Arcadia, CA, 1991 (This computerized database is much more thorough — with over a thousand entries — and much more scientifically rigorous — as with scientific nomenclature — than the database you are now using, more for general interest.).

Hogue, Charles L., and Fred S. Truxal, The Insect Realm: A Guide to the Hall of Insects, Los Angeles County Museum of Natural History, 1970.

Little, V. A., General and Applied Entomology, 3rd edition, Harper and Row, Publishers, Inc., San Francisco, 1972.

Swan, Lester A., Beneficial Insects, Harper and Row, Publishers, New York, 1964.

Swan, Lester A., and Charles S. Papp, The Common Insects of North America, Harper and Row, Publishers, Inc., San Francisco, 1972.

USAF, Captain Terry L. Bierry, Venomous Arthropod Handbook, 1977.

USDA, Insects: The Yearbook of Agriculture 1952.

Ware, George W., Complete Guide to Pest Control — With and Without Chemicals, Thomsom Publications, Fresno, CA, 1980.

Yepsen, Roger B., Jr., editor, Organic Plant Protection, Rodale Press, Inc., Emmaus, PA, 1976.

Back to Top

Sample Entry: Ladybird Beetles, or Ladybugs

Note: Numbers in parentheses are code numbers for computerized cross-references (precursors of modern-day hyperlinks) as well as for illustrations in the accompanying booklet.



Often brightly colored and patterned. The oval to almost ball-like body is very bulging on top but very flat below. The short antenna has a three- to six-segmented club. The head is at least partly hidden below the top of the thorax.

The pale- to dark- or brightly-colored larvae look like little alligators.




The adults and larvae usually live around their prey (below).


Ladybugs have hefty appetites — one larva [an “aphidwolf”] can eat over two dozen aphids a day, and one adult can eat over twice that much!

Generally, reddish-orange ladybugs eat aphids; the darker ones more often eat spider mites (6), whiteflies (41), and scale insects (46).

Overall, the prey of ladybugs includes mites (5), spider mites (6), springtails (12), thrips (23), lace bugs (28), chinch bugs (32), leafhoppers (37), perhaps treehoppers (38), psyllids (40), whiteflies (41), aphids (42), gallmaking and/or woolly aphids (43), pine and/or spruce aphids (44), scale insects (46), mealybugs (47), such other ladybugs as the Mexican bean beetle (65) [one of the few plant-eating species of ladybugs], asparagus beetles (70), the Colorado potato beetle (72), perhaps flea beetles (73), the elm leaf beetle (82), weevils (83), perhaps the diamondback moth (105), leafrollers (112), the European corn borer (117), sphinx moths and/or hornworms (130), cutworms and/or related caterpillars (138), the corn earworm (139), the stalk borer (142), and webspinning and/or leafrolling sawflies (157).


Although a very few are important pests (65), most ladybugs are among the most beneficial of all insects.

In many avocado orchards in Southern California, ladybugs and other beneficial insects control pests so well that virtually no chemical controls have been needed. In addition, the brown and orange “vedalia” lady beetle provided the first, classic example of modern biological control (See scale insects (46).).

Life Cycles

There may be a dozen or so generations a year (below).

Physical Controls

Plantings of yarrow reportedly attract ladybugs. In addition, there are commercially available aphid-scented lures to attract such natural enemies as ladybugs!

Beneficial species of ladybugs have often been intentionally imported into areas plagued by insect pests.

Typically, masses of the overwintering adults are collected in Pacific Coast mountains and are then either distributed in crop areas or kept in captivity for the rest of winter and sold in spring.

Although native ladybugs are usually the most efficient in a given area, imported ladybugs often work well, especially against pests accidentally imported from the same area.

See “Biological Controls” for some commercial sources of ladybugs, also available at many retail garden shops.

How many ladybugs will you need? Well, the answer varies with the source you consult. Typical answers are: 1/2 pint per one small garden or 1/4 acre; or one quart per acre; or 30,000 ladybugs per 10 acres — once again depending upon who you consult, there are 9,000 ladybugs per pint; 135,000 ladybugs per gallon; or 1,500 ladybugs per one ounce of weight. Follow label directions. Prices are typically reasonable.

There are precautions to take in releasing ladybugs. To prevent starvation in or migration from an area, do not put ladybugs out too early in the season. It is best to keep ladybugs hibernating in their container in the crisper compartment of the refrigerator (not the freezer) until there are enough pests out to keep the ladybugs well fed. Each box of ladybugs should be placed near plants and not too near other boxes of the beetles. If you remove them from the boxes, handle the ladybugs gently, so that they will not instinctively fly away in “fear.” To prevent ladybugs from flying away (as they often do, to burn-off excess winter fat after finally being released from hibernation and captivity), release ladybugs late in the afternoon or, better yet, at sundown: They will not fly at night, and many will become established in the release area by the next day. Keep the soil moist, as with a mulch, to give the ladybugs a safe place in which to hide.

Ladybugs can reportedly be “preconditioned” to prevent their flying away. For five days keep the ladybugs in a 4' x 6' x 4'-high tightly screened cage in the release area and daily spray the plants inside with one pound of “wheast” (a high-protein byproduct of the cheese industry, available as “Formula 57”) and one pound of sugar in one gallon of water (This mixture will also attract native ladybugs and lacewings, but perhaps also ants and, after the cage is removed, wasps and bees — this extreme method should be tested first.).

Another method to prevent losses of ladybugs by their flying away is to release them over wide areas: This, of course, requires cooperation between neighbors or within garden clubs or other community organizations, whose members should all benefit from decreased pest control expenditures, especially in the long-run.

In warm, sunny weather, released adults will mate and lay eggs in a day or two. In about two weeks a new generation of larvae will hatch-out and start eating their insect prey. Winter is spent in the adult stage, usually in groups of up to a million individuals, wherever there is shelter (especially from rain), usually in the mountains. In and around such areas, they eat enough pollen, plant sap, and the like to double their body weight before hibernation: This should be considered before releasing masses of ladybugs near mountainous areas in which valuable fall crops of such products as seed are grown.

Overall, ladybugs are valuable garden friends, asking for no more than something to eat — namely, our pests.

Chemical Controls

The use of many insecticides, especially such chlorinated hydrocarbons as DDT, has unintentionally killed many valuable ladybugs.

Biological Controls

Viruses infecting ladybugs include Iridescent Virus.

Bacillus thuringiensis, widely used vs. caterpillars (100), is reportedly nontoxic to lady beetles.

Fungi infecting ladybugs include Beauveria bassiana.

“Nematode” round worms parasitizing ladybugs include Agamermis decaudata, Mermis nigrescens, and Steinernema [Neoaplectana] carpocapsae.

Insects etc. parasitizing or preying upon ladybugs include mantids (15), stink bugs (24), damsel bugs (30), minute pirate bugs (31), assassin bugs (33), lacewings and/or aphidlions (48), various beetles (50), tiger and/or ground beetles (51), ladybugs (64), various (true) flies and/or maggots (143), robber flies (146), flesh flies (154), tachinid flies (155), braconids (159), perhaps “chalcidid” chalcids (161), “encyrtid” chalcids (161), “eulophid” chalcids (161), “pteromalid” chalcids (161), and ants (166) [In particular, those ants that carry and “milk” such honeydew-producing insects as aphids (42) will ward off some of the aphidwolves preying on their “livestock herd”!].

In a complex garden ecosystem, low levels of all these organisms could co-exist, keeping pest levels likewise low.

See Also

Beetles, including grubs and weevils (50), and the Mexican bean beetle (65).

Back to Top

Sources of Copyright-Free Illustrations for the Accompanying Booklet

Drenkow, Doug, Gardening with Insects, 1985.

Hart, Harold H., general editor, Pam Pollack, compiler, The Animal Kingdom, Hart Publishing Company, Inc., New York, 1977.

Harter, Jim, Animals ... A Pictorial Archive from Nineteenth-Century Sources, Dover Publications, Inc., New York, 1979.

Michelet, Jules, The Insect, Giacomelli, illustrator, T. Nelson and Sons, New York, 1875.

USAF, Captain Terry L. Bierry, Venomous Arthropod Handbook, 1977.

USDA, The Basic Principles of Insect Population Suppression and Management, Agriculture Handbook No. 512, 1979.

USDA, Beekeeping in the United States, Agriculture Handbook No. 335, 1980.

USDA, Control of Insects on Deciduous Fruits ... Without Insecticides, Home and Garden Bulletin No. 211, 1981.

USDA, Insects and Diseases of Vegetables in the Home Garden, Agriculture Information Bulletin No. 380, 1980.

USDA, Insects and Related Pests of House Plants, Home and Garden Bulletin No. 67, 1978.

USDA, Insects on Trees and Shrubs Around the Home, Home and Garden Bulletin No. 214, 1980.

USDA, Insects: The Yearbook of Agriculture 1952.

USDA, Lawn Insects: How to Control Them, Home and Garden Bulletin No. 53, 1980.

USDA, various other publications.

Back to Top