Bees can be protected from bee pesticides only by close
cooperation among growers, pesticide applicators, and
beekeepers.
 
Attempts should be made to avoid using any pesticides, even
those considered non-toxic to adult bees, unless absolutely
necessary. Bees foraging in almond flowers treated with captan
can return with enough chemicals to damage the colony. Captan
does not affect adult bee, but larvae exposed to this material may
die or develop into malformed adults. Whether or not captan is
unique in its effects will be determined by experimentation with
other fungicides and herbicides.
 
Treating large areas or repeating applications may cause greater bee kills. With few exceptions, pesticides applied as dusts are more hazardous to honey bees than those applied as sprays.

Pesticide spray formulations are often more hazardous to bees than are either emulsificable or water-soluble concentrate formulations.

Fine sprays are less toxic than coarse sprays. Sprays of undiluted technical pesticide (ULV) may be more toxic than diluted sprays. Aerial application of pesticides over bees in flight are more hazardous than ground applications. Granular applications are usually the safest method of treatment. Baits containing pesticide on materials such as apple pomace may attract bees resulting in death.

More than one pesticide is often applied in one treatment in California to control the entire pest complex present. Combinations of pesticides are less hazardous to bees than are the same pesticides used separately (as shown over the past 6 years of over 35 combinations of two to four pesticides used simultaneously). Using specific pesticides for each pest often enables the grower to select chemicals which are less hazardous than when using a high dosage of a broad-spectrum pesticide. Combinations of pesticide reduce the application costs and the number of treatments. Pesticidal contact with bees in reduced and thus bee mortality is reduced.

Time of application and location of colonies may be important in relation to bloom period and attractiveness of the forage crop to honey bees. Treating when bees are foraging in the field is usually the most hazardous, and treating over colonies in hot weather when bees are clustering on the outside of the hives may cause severe losses. Treatments during the night and early morning before bees are foraging are safest. Treating a nonblooming crop with a hazardous pesticide, when cover crops weeds, or wildflowers are in bloom in the field or close by may cause heavy bee kills. Pesticide drift to neighboring fields that are attracting bees may cause losses.

 

Effects of more than 600 pesticides have been measured on honey bees since these studies began in 1950. Relative toxicity to bees of 261 of these chemicals and many of their characteristics are given the most common are listed below with their toxicity. These ratings are based on field test in agricultural crops.

High, 1 day to 2 weeks Hazardous to honey bees at any time

* Restricted-use pesticide; may be purchased and used only by certified applicators.

Take care to use the proper dosage to the safest pesticide near bees that will give good pest control. Read the label and follow approved local, state, and federal recommendations. When using pesticides hazardous to bees, notify the beekeeper so that measures can be taken to protect colonies, or so that prompt, intensive care can be administered following poisoning the alleviate further damage.

It is the obligation of the beekeeper to post his name, address, and telephone number on his colonies and to register the locations of his colonies with local authorities. Thus, the pesticide applicator is made aware that colonies are present and that the names and telephone numbers of beekeepers are available for notification.

1. Notify the Agricultural Department in destination county. Stanislaus Ag. 209-525-4730, Merced Ag. 209-385-7431, San Joaquin Ag. 209-823-9305