Even sublethal amounts of neonicotinoids can be detrimental to bees and other pollinators by disrupting their ability to navigate or forage. Herbicides that eradicate important forage plants for bees and other pollinators also present a threat. Learn more about pesticides and how to avoid using them.

Air pollution contributes to the problem by disrupting bees’ and other pollinators’ natural ability to detect floral scents.^[2] When plant-emitted scent molecules interact with air pollutants, the molecules begin to break down. This confuses bees, causing them to spend more time foraging and less time pollinating.

While not as widely recognized, light pollution (brightening of the night sky caused by street lights and other man-made sources) also has a disruptive effect on insect communities and overall ecosystem balance. Research has shown that artificial light at night has a direct impact on the growth, flowering time and yield of plants, which ultimately affects bees and other pollinators.^[3]

Without flowers to visit, bees can’t find nectar for energy or pollen to feed their offspring. Without access to safe nesting sites, bees have nowhere to lay eggs to ensure future generations.

About 70% of native bee species are ground-nesting — they need areas of bare, undisturbed dirt to tunnel below and build their nests. In cities, these bees lose their habitats when loose soil is compacted by heavy foot traffic, when landscapes are paved with concrete and when lawns and public green spaces are frequently mowed and overly manicured. We can all help restore much-needed habitat by creating our own pollinator-friendly gardens and by urging our local officials to establish more bee-friendly spaces.

Pollinators’ habitats also decline when they are disconnected from each other by road construction, development or agriculture. Creating safe passages and corridors between such isolated patches of habitats helps pollinators survive in these areas. Roadsides, for instance, are an important yet often overlooked opportunity. Those planted with native grasses and wildflowers — and mowed less often during the growing season — help create refuge and connect fragmented pieces of habitat. Likewise, the practice of planting trees, hedgerows and large strips of wildflowers along field edges also provides more nesting sites and forage sources for pollinators (not to mention the numerous benefits for other wildlife).^[4]

In other words, the time when flowers decide to bloom must match with the time when bees decide to forage. Gradual changes in long-term weather patterns — including temperature, rain and sunlight — can alter environmental cues and disrupt this delicate balance.

For example, warmer-than-usual temperatures affect the time of day certain plant species produce flowers, nectar and pollen. Some bees, on the other hand, may respond by altering the time of day they choose to forage (or limiting their forage distance) to avoid overheating. Unseasonable warmth or increased precipitation may prompt crops to flower earlier in the growing season, before their primary pollinators have emerged.

Bumblebees are among those species who may be most vulnerable to the consequences of a shifting climate. They have thick coats of hair which makes them better suited to cooler weather, so they struggle to adjust (behaviorally and physiologically) when temperatures spike outside the typical range. Bumblebees’ geographic range includes higher altitudes and latitude areas where climate change is most dramatic, and the nature of their annual life cycle means their populations show responses to such change more quickly. Findings from a study published in 2017 found that populations of three bumblebee species in Colorado were impacted by indirect effects of climate on flower distribution throughout a season.^[5]

In urban areas especially, spaces that lawns occupy have huge potential to not only create pollinator habitat and support more biodiversity, but also to make cities more sustainable and climate-resilient. Turf grass lawns have a higher surface temperature compared to plots with more plant volume. So, incorporating a diversity of taller flowers and shrubs can help create a cooling effect to reduce urban heat islands.^[6]

Honeybees’ most dangerous enemy is the varroa mite, which feeds on the blood of adult honeybees and reproduces on honeybee pupae. Varroa mites spread among colonies via drifting workers and drones, along with the robbing of honey from infected hives. Once present in a colony, varroa weaken bee immune systems and transmit a variety of deadly viruses including deformed wing virus.

The mites (and the viruses they transmit) are considered one of several culprits contributing to Colony Collapse Disorder. This occurs when the worker bees disappear from a hive. With no mature bees to bring nectar and pollen back to the queen and younger bees, the colony collapses and dies. Despite certain treatment methods for varroa mites and some diseases, these pervasive threats continue to pose a major challenge to beekeepers and honeybee populations.