Using Beneficial Insects to Combat Pests

Using Beneficial Insects to Combat Pests

You know the frustration caused by pesky pests that ravage your crops!? Well, we’ve been battling the cucumber beetle on our farm since we started growing crops here. This year the cucumber beetles have been feasting on our dahlias - they especially love the young and tender leaves that have just emerged from the soil. Just one cucumber beetle can destroy an entire plant by eating all the greenery. Their larvae on the other hand feed on the roots. So our dahlias have been getting attacked from above and below the surface!

Spotted Cucumber Beetle on a dahlia leaf

After collecting the beetles by hand, crushing them and spraying an organic pesticide, I’ve decided to try another way…beneficial insects!

I’ve purchased 3 different beneficial predators to attack the cucumber beetles from different angles: Green Lacewings, Assassin Bugs, Beneficial Nematodes.

1. Green Lacewing: Nature's Graceful Predator

Green Lacewing

[image from Arbico Organics]

Green Lacewings, also known as "aphid lions” have a voracious appetite for a variety of pests, including cucumber beetles and their larvae. The larvae of Green Lacewings are particularly effective at controlling these beetles and other soft-bodied insect pests. Adults feed on nectar, pollen, and honeydew - perfect for a flower garden that will help keep the adults around to lay eggs for the next season!

Green Lacewings eggs will take about 3-10 days to hatch. Once hatched, green lacewing larvae roam plant foliage looking for prey – pest eggs, nymphs or adults. They feed for 2-3 weeks, spin a cocoon, and emerge as adults 10-14 days later.

Application: Mist down plants lightly before releasing green lacewing. Gently shake the vial containing the lacewing eggs and bran. Tap contents out onto foliage. Distribute as evenly as possible throughout the affected area.

2. Assassin Bugs: Nature's Vigilantes

Assassin Bug

[image from Arbico Organics]

These predatory insects are renowned for their piercing mouthparts, which they use to suck out the bodily fluids of their prey. Both the nymphs and adults of Assassin Bugs are skilled hunters and feed on a wide range of garden pests, including cucumber beetles, aphids, mealybugs, caterpillars, and thrips.

It can take up to 10 days for the Assassin Bug eggs to hatch. They begin feeding as soon as they emerge. Once they reach 2nd instar, they will actively hunt for prey and continue to do so as they mature into adulthood. 

Application: The eggs of the Assassin Bugs come on a little piece of cardboard. To release, hang or place egg clusters within foliage in areas with high pest populations.

3. Beneficial Nematodes: Silent Soil Warriors

Microscopic image of Nematodes

[image from Gardener's Path]

Since both the Green Lacewings and Assassin bugs will take a little while to hatch I wanted to apply something that could start working right away. 

Beneficial nematodes are microscopic roundworms that parasitize and kill the larvae of cucumber beetles and other soil-dwelling pests. While the Green Lacewing and Assassin Bugs will tackle cucumber beetles above ground, beneficial nematodes will combat these pests below the surface. 

Application: To release, mix the beneficial nematodes “powder” with water and spray directly into the soil.

A few tips:

  • Apply or release early in the morning or pre-dusk when temperatures are cooler and the sun is not so bright.
  • Pre-moisten the soil.
  • Read the instructions carefully before application!

I love ordering from They ship quickly and have detailed educational instructions.

And remember: a diverse and balanced garden ecosystem typically includes a variety of organisms, including beneficial insects, pollinators, and even some pests! These various organisms contribute to the overall health and vitality of the garden. So, while it's important to manage pests to prevent significant damage, a complete absence of pests may suggest an imbalance in the ecosystem.

I would love to know what pests you have been dealing with! Drop me a comment below.


P.S. I would not recommend ordering ladybugs as you can easily attract native ones and I do not agree with the harvesting practices used by the companies that collect them. 

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