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Use caution when applying insecticides in the garden during blossoming to protect pollinators

Bob Dluzen
Special to The Detroit News

New gardeners may not recall the relationship between flowers and the formation of produce. For virtually all above ground vegetables, flowers come first, then are pollinated by insects, wind or other means. Crops harvested for their underground parts, such as carrots, or those harvested for their leaves, do not require pollination except when seeds are wanted.

Pollination is a two-part process. One part is responsible for the development of seeds while the other is responsible for the development of the fleshy part of a vegetable or fruit.

In the vegetable garden, insects do most of the pollination and it happens when they forage for nectar. This is especially true for crops like cucumbers, squash, melons and other fleshy vegetables. Some such as peppers, beans, peas and a few others, are not normally pollinated by insects, but occasionally will be.

Honeybees are the first insects that come to mind when we think of pollinators. There are, however, many wild bee species that also pollinate our garden crops. The domesticated and wild bees together are responsible for 50 to 75 percent of pollination, depending on the crop and local insect populations.

The remainder of the pollination duties are taken up by other insect groups such as wasps, moths, butterflies, ants, beetles, flies and others. Together this non-bee contingent is responsible for an average of 39 percent of pollination. So, there is a lot going on in the garden that we don’t necessarily notice.

As pollinators, beneficial insects can improve both the quality and quantity of a crop. They will often visit hard to reach flowers that honeybees pass by resulting in fruit that would otherwise not have formed. Also, the other pollinators will approach flowers in a different way because of their body shapes. That can result in more complete pollination resulting in larger and better-quality fruit.

During peak flowering under good conditions, there can be a lot of competition for nectar with many different insects jockeying for the best flowers.

There was a lot of pollinator action on my cucumbers this week. Here’s a wild bee zooming in to drive a honeybee away from this cucumber flower.

People are concerned about insects attacking their crops and rightly so. But it is important to differentiate the good from the bad insects. The vast majority of insects we see are either harmless or beneficial. It’s very important not to automatically reach for the bug killer whenever an unidentified insect is spotted in the garden.

It is vital that gardeners be extra careful with insecticides around flowering plants. Most insecticides will kill pollinators just as easily as they kill pest insects. Exceptions would be biological agents such as Bacillus thuringiensis (Bt) and similar materials.Those types of materials contain bacteria that only infect target species and are harmless to non-target insects.