Skip to content Skip to navigation
UMass Collegiate M The University of Massachusetts Amherst
  • Visit
  • Apply
  • Give
  • Search UMass.edu
Center for Agriculture, Food, and the Environment
UMass Extension Landscape, Nursery and Urban Forestry Program
  • LNUF Home
  • About
    • Program Overview
    • Faculty & Staff
    • Contact Information
    • Disclaimer
  • Newsletters & Updates
    • Landscape Message
    • Hort Notes
    • Garden Clippings
  • Publications & Resources
    • Fact Sheets
    • Weed Herbarium
    • Professional Disease Guide
    • Professional Insect & Mite Guide
    • Nursery Best Management Practices (BMP) Manual
    • Garden Calendar
    • Useful Links
    • Association Certification
    • Pesticide License Information
    • Pesticide Resources
    • Nutrient Management
  • Services
  • Education & Events
    • Events
    • News
    • Green School
    • Invasive Insect Certification
    • Invasive Plant Certification
    • Turf Winter School
    • InsectXaminer
    • Invasive Insect Webinars
    • TickTalk with TickReport Webinars
    • Pollinator Steward Certification Program
  • Make a Gift

Bacillus thuringiensis (B.t.)

What is B.t. ?

B.t. is the abbreviation for a species of bacteria, Bacillus thuringiensis, commonly found in nature. These bacteria can live and multiply within the bodies of insects, and produce spores and protein crystal toxins which can result in death of the insect host. In order to work as a biological insecticide, B.t. or its spores or crystal toxins must be must be eaten by the insect. Inside the insect, the crystal toxins bind to cells of the gut wall, and cause these cells to break apart. Within minutes of eating B.t, the insect stops feeding. Death will occur, primarily by starvation, in about 2 to 5 days.

Why use B.t.?

B.t. is considered non-toxic to plants and to animals other than certain insects. It is highly selective, and only kills certain insects. It does not kill most beneficial insects such as lady beetles and parasitic wasps. B.t. is also non-polluting and can be safely used where other pesticides may cause contamination to surface and groundwater. B.t. is cost effective when compared with other pesticides.

What pests does B.t. control?

B.t. is effective against the larvae, or immature stages, of insects but not the adult stages. There are many strains of B.t., and each is most effective against certain insect pests. Some of the strains include:

  • B.t. var 'aizawa' - for control of larvae of wax moths and other moth species
  • B.t. var 'israelensis' - larvae of mosquitoes, black flies, and other flies
  • B.t. var 'kurstaki' - many types of caterpillars
  • B.t. var 'San Diego' - larvae of elm leaf beetle
  • B.t. var 'tenebrionis' - larvae of elm leaf beetle

How should B.t. be applied?

  1. Choose the right product, i.e. the proper strain, of B.t. for the insect to be controlled.
  2. Avoid high pH water when mixing B.t. sprays since high pH can reduce effectiveness.
  3. Use B.t. spray within 12 hours of mixing.
  4. Time applications to coincide with most vulnerable life stage of pest.
  5. Add a spreader/sticker to the tank mix to improve the effectiveness of the spray. Reapply the spray if heavy rainfall occurs within 8 hours of application.

Written by: Ron Kujawski
Revised: 10/2011

Connect with UMass Extension Landscape, Nursery and Urban Forestry Program:

Facebook   Twitter

Subscribe to GreenInfo Mailing List »

Home Lawn & Garden Information »

Center for Agriculture, Food, and the Environment

 

Stockbridge Hall,
80 Campus Center Way
University of Massachusetts Amherst
Amherst, MA 01003-9246
Phone: (413) 545-4800
Fax: (413) 545-6555
ag [at] cns [dot] umass [dot] edu (ag[at]cns[dot]umass[dot]edu)

 

Civil Rights and Non-Discrimination Information

College of Natural Sciences

Login for faculty and staff

CAFE Units

Mass. Agricultural Experiment Station

UMass Extension

UMass Research and Education Center Farms

UMass Cranberry Station

Water Resources Research Center

Interest Areas

Agriculture

Commercial Horticulture

Energy

Environmental Conservation

Food Science

Nutrition

Water

Youth Development & 4-H

Services

Pesticide Education

Plant Diagnostics Laboratory

Soil and Plant Nutrient Testing Laboratory

Hot Water Seed Treatment

Water Testing / Environmental Analysis Laboratory

Projects

Conservation Assessment Prioritization System (CAPS)

Extension Risk Management/Crop Insurance Education

Mass. Envirothon

Mass. Herp Atlas

Mass. Keystone

MassWoods

North American Aquatic Connectivity Collaborative

RiverSmart

UMass Design Center in Springfield

Resources

Extension Sales Portal

Agriculture & Commercial Horticulture Resources

Community & Economic Vitality

Disaster Preparedness

Food Safety

Home Lawn & Garden

Integrated Pest Management (IPM)

Land Conservation Tools

Pollinators

Tick testing

Resources for Faculty and Staff

Extension Programs

4-H Youth Development

Agriculture

Crops, Dairy, Livestock and Equine

Fruit

Greenhouse Crops and Floriculture

Landscape, Nursery and Urban Forestry

Pesticide Education

Turf

Vegetable

Clean Energy

Climate Change

Food Science

Nutrition Education

Value-Added Food

Seal of The University of Massachusetts Amherst - 1863
©2025 University of Massachusetts Amherst · Site Policies · Accessibility