Urban Pesticides and Bees
Obviously the less you rely on insecticides in your yard, the better. Minimizing insecticide use can protect bees, save you money, and curtail the unnecessary release of toxins into the environment. Yet homeowners trying to determine whether to use an insecticide and attempting to select a responsible product face a bewildering series of decisions (Image 2 STORE AISLE). The following list will help you think about how to minimize insecticide use, with general tips on product selection.
Do you need to apply an insecticide?
Is it really insect / mite damage? Some common plant diseases can be easily mistaken for insect or mite damage (Image 3 PLUM LEAF SHOT-HOLE DISEASE). In addition, many abiotic stressors like wind, cold, sun scald, hail, late spring frost, and iron chlorosis can cause leaf or flower damage that can look remarkably like insect feeding injury. In such cases, application of an insecticide is a waste of money and a pointless introduction of toxic materials into the environment. For help determining what your underlying problem is, contact your county extension office. You can mail in or bring in a damage sample to the extension office for identification and control advice.
Is the damaging insect properly identified? Insects and mites have a remarkable range of feeding styles and life histories, and control efforts vary accordingly. For example, …
Do you understand the life stages of the pest? There is no point in applying an insecticide for a pest that has finished the damaging phase of its life cycle for the year (Image 4 PEAR SAWFLY), or has reached a life stage that a particular product can’t target effectively, such as protected egg clusters or pupae.
Have you considered alternatives to insecticides? [Hand-picking, removal of plants that are a perennial problem – replace with more resistant choices. Native plants are often a better choice … Ant-herding of aphids …] (Image 5 WILLOW REDGALL SAWFLY).
Do you recognize beneficial insects? Lady beetles, damsel bugs, big-eyed bugs, syrphid fly larvae, hunting wasp species, predatory mite species, lacewings, and many other arthropods are beneficial predators of foliage-feeding aphids, mites, thrips, caterpillars, beetles, sawflies, etc. Some feed on root pests and wood-boring pests as well.
Are you selecting an appropriate product? Read the product description carefully before you buy. Does it target the pest that needs to be controlled? Is it clearly labeled for home landscaping use? Is it labeled for use on the host plant(s) you intend it for? Does the product work via systemic activity (i.e., actively moved through plant tissues internally)? Does the pesticide work via contact activity?
Have you read the entire product label before using the product? Pesticide labels list information on correct storage, use, and disposal of pesticide products. For many reasons related to human health and environmental protection, it is vital to read pesticide labels thoroughly before application. For concerns specifically related to bee safety, read the “Environmental Hazards” statement in the label (Image 6 LABEL PAGE). This portion includes any bee toxicity statements and application restrictions intended to protect bees. Many bee warnings explicitly forbid application during flowering of the host plant as well as drift to flowering weeds in the immediate area. This can be a particular problem with perimeter sprays around buildings or lawn sprays to kill soil insects (?) if flowering weeds such as dandelions and clover are present. Note: Warning statements on labels are either probably referring to honey bees or they are explicitly so; unknown effects on bumble bees and solitary bees.
Is the host plant flowering? Bee warnings often explicitly forbid product use during flowering. This applies to ornamental garden plants, trees, and shrubs as well as flowering weeds (such as dandelions, an early spring favorite for many bee species) (Image 7) CLIPPED JOE-PYE WEED FLOWER HEAD. Not all ornamental plants are pollinated by animals. Some plants, such as elm trees, have flowers that are not visited by pollinators because they are wind-pollinated. As long as spray drift to neighboring flowers is eliminated, wind-pollinated plants such as elms, conifers, aspen, cottonwood, black walnuts, boxelder, and ornamental grasses can generally be treated safely with respect to bees and other pollinators.