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| Tomato Hornworm parasitized by Braconid wasp cocoons |
Both Braconid wasps and Syrphid flies are almost too small to see. Unless we really pay attention, we won’t notice them in our garden. Despite their minuscule size, they are an important part of integrated pest control (IPM).
Braconid Wasps
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Braconid wasp parasitising Caribbean fruit fly larvae in a guava, Photo byJeffery Lotz, Division of Plant Industry, IFAS |
For instance, Braconid wasps, such as Cotesia congregata, are members of the Braconidae family, which has about 17,000 species known and many thousands more as yet unidentified. The Cotesia wasps lay up to 200 eggs a day under the skin of tomato and tobacco hornworms, the pests that munch on our tomatoes. When braconid larvae emerge (2-3 days later), they begin feeding within the hornworm, essentially eating it alive. The growing larvae will emerge in about 12-16 days and spin the white cocoons seen in the picture above where they will pupate for 3-8 days. Cocoons often fall off the host into the soil, where an adult wasp will hatch.
Other brachonid species parasitize cabbage worms and other soft-bodied pests, such as army worms, loopers, aphids, whitefly, mealybugs and scales, stink bugs and leaf miners. They also parasitize many other insect groups, especially moths and butterfly larvae, beetles, flies, ants, bees, and other wasps.
Braconid wasps are attracted to the nectar and pollen of flowers, especially those with small florets. Some plants that attract them include most herbs such as dill, fennel, and parsley; also marigolds, daisies, sweet alyssum, carrot family plants and buckwheat. Read about the results of a field experiment to attract predator insects conducted near Live Oak. https://projects.sare.org/project-reports/os13-079/
Braconid wasps are also attracted to the smell of caterpillars munching plant leaves. You can attract Braconid wasps by allowing caterpillars to feed until the tips of the braconid cocoons open. You will see a little black dot at the end of the cocoon when they have opened.
https://pacifichorticulture.org/articles/braconid-wasps/
Syrphid Flies
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| Adult female Syrphid Fly, Photo credit, Roy Frye |
Adults look like bees, but they have only one pair of wings. You can usually find them hovering in one spot, as they are expert fliers and can hover or fly backward, abilities possessed by few other insects. Adults often visit flowers for nectar. They may also be seen around aphid colonies where the female syrphid fly feeds on honeydew secreted by the aphids. Syrphid fly eggs are laid singly on the surface of a leaf or twig that bears aphids. When larval populations are high, syrphid flies may kill 70% to 100% of an aphid population.
While syrphids concentrate mostly on aphids, they also parasitize other soft body insects. Adult syrphid flies are also considered to be important in the cross-pollination of some plants. Most species mimic bees and wasps, so they are often mistaken for stinging insects, but they are not harmful to humans.
These two tiny predators are just the tip of the iceberg. There are many, many other parasitoid insects. We just need to omit pesticides and provide conditions to attract them, such as flowering plants, a water source, and leaf litter or twigs where they can overwinter.
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