Read and Follow the Label

The label will indicate if a pesticide is toxic to bees when the application contacts them directly or by residues. Before using the pesticide, look under the “Environmental Hazards” and “Directions for Use” headings for any precautions that need to be taken. See the following example.

This pesticide is highly toxic to bees exposed to direct treatment. Do not apply it or allow it to drift to crops or weeds on which bees are actively foraging

Don’t assume that all bee cautionary statements are the same. The subtle differences regarding treating plants while bees are VISITING, or treating plants while bees are ACTIVELY VISITING, are important to assure adequate protection for pollinators. Some labels warn against the use of the product on blooming crops by stating “Do not apply to blooming crops or weeds if bees are VISITING in the treatment area.” “Visiting the treatment area” refers to bees that may visit the plants after treatment (the bees may or may not be working the crop at the time when the pesticide application is planned) and pertains to products that do show Residual Toxicity**; such products require a higher level of care in avoiding pollinator exposure by not applying them while the crop is in bloom. Realize that the application “window” (period when the timing is right) may be reduced due to factors such as extended crop bloom or unfavorable weather conditions (see Pesticide Applicator BMPs). “Actively visiting the treatment area” refers to bees you see on plants and pertains to products that do not show Residual Toxicity. In current labeling, any reference to bees “actively visiting,” “actively foraging,” or “visiting,” must be replaced with “FORAGING.”

2014 Labeling changes for certain Neonicotinoid Pesticides:

EPA requires that labels for products containing clothianidin, dinotefuran, imidacloprid or thiamethoxan that have use directions for outdoor foliar application include a “Pollinator Protection Box” (click here to view), as well as new pollinator language (click here to view) to be added to the Directions for Use section of each label. In Aug, 2014, the Association of Structural Pest Control Regulatory Officials (ASPCRO) submitted a “Guidance Document for Bee Language for Neonicotinoid Products in Outdoor Structural and Turf and Ornamental Settings” to EPA. The EPA agreed that the interpretation of the new labeling statements by ASPCRO was appropriate and have concurred with the document.

**Residual Toxicity Defined (from California Department of Pesticide Regulation)
Residual Toxicity (RT) time is that period of time after completing a pesticide application until there is minimal toxic effect to bees. The RT time is specified on product labeling and is based upon Residual Toxicity25 (RT25) studies. The RT25 studies determine 25% bee mortality based on the test bee populations exposed to the formulated pesticide product applied to foliage. It is believed that 25% of the colony can be lost and the colony can regenerate. Pesticides with RT25 values lower than 8 hours present a minimal hazard if they are applied during late evening or night. Pesticides with RT25 values greater than 8 hours cannot be safely used when they might contaminate bee forage.

Residual Toxicity (RT25) is very useful information, but it is not available for all pesticides. Systemic pesticides are not considered in RT25 assessments; it is based solely on surface contact and exposure. The U.S. EPA has compiled data of RT25 values for various active ingredients.


Compiled by Wayne Buhler, PhD.

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