Integrated Pest Management for Three Pesky Insects

Allen County SWCD use IPM on three common pests with Purdue Professor of Entomology Lauren Ingwell

In a 2022 Coffee and Pest Management webinar, Dr. Laura Ingwell, an Assistant Professor in Horticulture Entomology at Purdue University, described Integrated Pest Management for three different pests. Dr. Ingwell takes a look at cabbage worms, aphids, and cucumber beetles.

If you want to learn more about our “Coffee and” webinars, be sure to check the page on our website. Learn more about our Urban and Small Farms Program to see if you are eligible for free soil testing and other services.

Integrate Pest Management (IPM) is an “ecosystem-based strategy that focuses on long-term prevention of pests and their damage through a combination of techniques.” IPM uses variety/cultivar selection, timing, location, habitat manipulation, biological controls, and as a last result, pesticides to manage the pests in your farm and garden.

Cabbage Worms

Cabbage worms eating cruciferous plant. Allen County Soil and Water Conservation District SWCD Integrated Pest Management Webinar.

Cabbage worms go through complete metamorphoses. Larvae are the dangerous form of this insect to our plants. The bigger the larvae get, the more they eat the plant. Once they complete their larval stage, they go through a pupal phase where they make the transition to adulthood. After the adults mate, they lay eggs. The best way to manage cabbage worms is preventing the adults from laying eggs on your plants. If you’re too late, you can address them as small caterpillars.

Crop selection can be used to prevent cabbage worms. Take notes and see which crops are chewed most in your garden, avoid planting those the following year. Another tool is exclusion. Use low tunnels to add a physical barrier keeping the moths from making contact with your plants. Biological controls such as tachinid flies, parasitic wasps, and predatory stinkbugs are natural enemies to cabbage worms. Chemical controls are a last resort, but foliar sprays of Bt are an effective organic option.


Aphids eating crops. Allen County Soil and Water Conservation District SWCD Integrated Pest Management Webinar.

Aphids are small and sneaky. They feed on plants with a sucking mouthpart much like a straw. They can kill seedlings and young transplants and vector plant viruses. Thier direct feeding on plant sap results in excess sugar that the insect excretes in the form of honeydew. The honeydew attracts other insects, like ants, wasps and bees, and also facilitates the growth of sooty mold, a black-white powdery substance which inhibits photosynthesis. Aphids undergo incomplete metamorphosis. The juveniles look like miniature versions of the adults. They also give live births, so you won’t find any eggs. There are both winged forms, for long distance dispersal, and wingless forms. Cultural controls include monitoring your plants and the plants around them for the presence of aphids and their natural enemies. Biological controls include parasitic wasps, lacewings, ladybeetles, minute pirate bugs, and syrphid flies. If natural enemies are present, just monitor the population to see if they continue to build or remain the same/decline. If cultural and biological controls fail, chemical controls are a last resort. Horticultural soaps and oils can be effective in a home garden setting.

Cucumber Beetles

Spotted cucumber beetle. Allen County Soil and Water Conservation District (SWCD) Integrated Pest Management Webinar.
Spotted cucumber beetle.

There are two different species of cucumber beetles: striped and spotted. Striped cucumber beetles only feed on cucurbits, whereas spotted cucumber beetles are not as picky. All of them can transmit a bacterium that leads to bacterial wilt. There are two peak times during the growing season when adults are present and transmitting the disease – early spring when they are looking to feed and lay eggs and, in the late summer, when the second generation is preparing to overwinter in the soil. A major portion of their lifecycle takes place in the soil. Cultural controls include delayed planting. Waiting to plant any cucurbits in the spring prevents the adults that overwintered from finding food when they emerge from weedy habitat where they have overwintered. Mechanical controls include exclusion with a screen that will allow small beneficial insects in but not cucumber beetles. Spiders are a great biological control. Chemical controls such as foliar sprays and powders can be used but only as a last resort.

If you want to learn more about IPM other resources include the Purdue Consumer Horticulture website, the Purdue Entomology Extension Vegetable Website, the Purdue Entomology Extension Fruit Website, and the Purdue Plant and Pest Diagnostic Laboratory.

The Living, the Dead, and the Very Dead

Soil needs microbes, dead plant and animal matter, and carbon to become healthy. Compost is organic matter. Roots add to organic matter.

Organic matter makes up 1-6% of most soils. Organic matter (OM) is what makes your soil fertile. Soil biology can live and thrive in OM and so can your plants. Organic matter is derived from decomposed plant and animal materials, which supplies nutrients for organisms. It also forms different sized aggregates that aid in better gas and water exchanges in the soil. So, what makes up organic matter? OM is made up of three parts: the living, the dead, and the very dead.

The Living

Earthworms and other soil life are important for oranic matter and soil health.

The “living” part of organic matter is made up of the organisms that call soil their home. Bacteria, fungi, viruses, algae, moles, rabbits, woodchucks, plant roots, etc. are all considered living organic matter. Soil organisms make up 25% of the earth’s total biodiversity. In just a teaspoon of soil, there are tens of thousands of different organisms. Soil organisms have 3 main roles:

  1. Mix organic matter into mineral soil
  2. Stabilize soil aggregates and structure
  3. Make new chemicals and new cells in the soil

Microorganisms, earthworms, and insects feed on plant residues and manures for energy and nutrition. In the process, they mix OM into the mineral soil. Earthworms have a sticky substance on their skin that helps bind soil particles together. Other materials produced by fungi have a similar effect. These aggregates make up good soil structure. Roots and other organisms produce channels that stabilize soil structure and help with water infiltration. The sun puts energy into plants through photosynthesis. This energy ends up in the residue of plants after they die which microorganisms break down to create new chemical compounds.

The Dead

Plant residues from corn and other plants lend to healthy soil and organic matter.

The “dead” part of organic matter is made up of the fresh residues including dead microorganisms and earthworms, old plant roots, crop residues, recently added manures, etc. Fresh residues have 3 main roles:

  1. Main source of food for soil organisms
  2. Provide nutrients for living plants
  3. Improve soil structure

Soil organisms eat the dead organic matter for energy, breaking it down which releases the nutrients necessary for plant growth. As the living organisms decompose the dead material, they release chemical compounds that bind soil particles together and benefit soil structure.

Some residues are broken down by soil organisms more easily than others. Proteins, amino acids, sugars, and starches are broken down very easily. While lignin, which is a fibrous compound, takes much longer for organisms to break down.

The Very Dead

Decomposed plant materials make up the topsoil.

The “very dead” part of organic matter is made up of substances in the soil that have already been decomposed by soil organisms and are inaccessible for further breakdown. We refer to this as humus. Humus has 4 main functions:

  1. Slowly release nutrients to plants
  2. Protect plants from harmful chemicals
  3. Reduce compaction
  4. Improve water retention

Humus has a good Cation Exchange Capacity (CEC) and has the ability to bind to nutrients that are essential for plants. It slowly releases these nutrients for plants to utilize while reducing the risk of leaching. Some humus molecules can encase potentially harmful chemical compounds in order to protect plants from taking them up. Humus can rebound and prevent compaction problems while also reducing soil density, improving aggregation to hold onto and release water when necessary.

What do we learn from soil organic matter?

Organic matter is extremely important for nutrient availability for crops, soil structure, and water retention. Disturbing soil has effects on the living, the dead, and the very dead parts of organic matter. Tillage destroys the habitat of living soil organisms and aggregates of soil structure. It can also make humus (organic matter that is inaccessible for further breakdown) more accessible to soil organisms for decomposition, releasing carbon into the atmosphere.

Converting your growing operation to a no-till system is easily manageable and can even save you time and money! To learn more about growing no-till click here.


Magdoff, F., & Van Es, H. (2021). Building Soils for Better Crops: Ecological Management for Healthy Soils (Fourth Edition). Sustainable Agriculture Research and Education (SARE).