National Pollinator Week

This blog has been a lot about bees lately, and I will stick with this subject for just a little longer, because this week is National Pollinator Week.
You may know that without honey bees, there would be no almonds, peaches, apples, cherries, blueberries or strawberries in our super markets. Bees need to visit and pollinate the flowers of all of these plants, or there will be no fruit.

However, there are many more pollinators than just honey bees. In fact, in our garden, most flowers are visited by other insects, while the honey bees fly off to richer pastures (right now, to the linden trees across the street).

Over the last few days, I went to the garden in the morning and at night to document which pollinators I can find on our flowers.

Leaf cutter bees. Females collect pollen on their bellies, as can be seen in the top middle photo. On the bottom right is a leaf that has been “punched” by a leaf cutter bee.

I found the first signs of a different pollinator by looking at leaves, not flowers. Some leaves of of our roses had holes in them that looked as if someone had put a hole puncher to them. This is the work of leaf cutter bees (Megachile spp.). These bees do not live in colonies or hives. Every female makes her own nest inside of a hollow stem. She carefully lines it with the leaf circles that are missing from our roses, provisions this nest with pollen, lays an egg and seals the cell. It is thought that the leaf-lining prevents the growth of molds and bacteria that could spoil the food for the bee’s offspring. Our leaf cutter bees are about as large as a honey bee, but they are easily distinguished: while honey bees collect pollen on their legs, leaf cutter bees collect it on their bellies.

Long-horned bees. The upper right photo shows a female with short antennae. The bees with long antennae are males. On the bottom left, a male has just landed on a female. At night, male long-horned bee are asleep on their favorite sunflowers.

Since the first sunflower relatives opened their flowers, I always find Agile Long-horned Bees (Melissodes agilis). They seem to be really partial to flowers of the Aster family, and this is where they hang out for eating, foraging and for sex. In the morning, I could observe how males dive-bombed at females that were sitting on the flowers. A tussle ensued and both bees tumbled into the vegetation. Like the leaf cutter bees, long-horned bees are solitary. Therefore, there are as many males as females around. Males are distinguished by the very long antennae that gave these bees their name. At night, I found male long-horned bees huddled together on a sunflower. Sometimes there were one or two, once I saw as many as five. Long-horned bees build their nest in the soil.

Two tiny masked bees on a rose flower.

While long horn bees are also about the size of a honey bee, a careful look at the beautiful old garden rose “Apple Blossom” revealed that its flowers were visited by tiny black bees. These are masked bees (Hylaeus sp.), another species of bees that do not live in colonies. They build their nests hollow dead twigs. There is something to be said for a garden that is not perfectly tidy!

Bumble bees on milkweed and lavender.

Many kinds of flowers are visited by the common eastern bumble bee (Bombus impatiens). Bumble bees live in colonies, have a single queen and usually build a nest in the ground, often in an abandoned rodent burrow. I saw quite a few bumble bees and suspect that their nest is somewhere in our garden.

An Eastern carpenter bee rests on a hydrangea flower.

While the masked bees were the tiniest bees I could find, the largest one was an eastern carpenter bee (Xylocopa virginica). Carpenter bees build their nests in holes that they chew into wood. Many home-owners are not happy when they see these big insects hover near their houses. We don’t have to worry: our shed is made of metal and  carpenter bees come to our garden only to forage.

A Cabbage White butterfly (Pieris rapae) enjoys lavender nectar.

Not all pollinators are bees. On my morning walk, I also saw butterflies. Finally, there are moths, wasps, flies and beetles that visit flowers and play a role in pollination. If we are lucky, we may even see a hummingbird.

Flies are pollinators, too. This one sits on a celery flower.

It is wonderful to know that all of these diverse insects come to our small patch of green in the middle of New York City!