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Sunday, August 30, 2009

Metallic green bee, a good pollinator

The pure golden green bee, Augochlora pura, is a singular bee, smaller than a honey bee and looking like a shiny metallic little robot bee. There are several other metallic green bees related to this, they compete in beauty and they are all good pollinators of many wild flowers.

In the spring she builds her nest under the bark of rotten logs. If you thought that dead trees or large dead branches had no use you were wrong. To this very nice pollinator they are prized real estate, just the right place to raise her family safely and well protected. She searches for the right dead tree diligently and, if your garden is one of those perfectly manicure ones, you will not have the pleasure of her and her family's company.


She builds a small chamber in the space between the loose bark and the solid wood using her own saliva and secretions. She packs it with a storage of pollen and nectar very carefully kneaded and shaped as tiny loaves. She encrusts the inner walls of the chamber with these loaves arranged like tiles. When she has enough to feed one baby from birth to maturity she lays a small egg and shuts the chamber. She surrounds it with loose debris which abounds in such places and starts the construction of other chambers. You may find a couple of rows of four or five of these cells. The mother bee dies at the end of the summer and the new generation spends the rest of the year comfortable and safe until the next spring.

Tuesday, August 25, 2009

FLOWER FLIES. Very Good Friends of the Gardener

There are some little flies that visit flowers with great frequency. Naturally, they are called flower flies; although the British prefer the name "hover flies", which describes their behavior very accurately. They are very numerous in the garden; but if you dislike house flies you don't need to worry about flower flies; they are rather pretty. You probably didn't notice their presence thinking that they were bees, rather than flies.They are excellent impersonators of stinging insects such as bees and wasps and they probably fool hungry birds into thinking that they may get stung but these little "bees". This strategy seems to work very well for them, so they can go feeding on flowers unmolested by these winged predators.

Sphaerophoria

In their visits to flowers they accomplish some pollination. They may not be as efficient as bees, but their sheer abundance makes them important pollinators of wild flowers. But there is something else that these flies do that makes them very welcome in the garden: The larvae of some of them feed on aphids.


This is such an important task that they deserve more attention than they get from plant lovers. We don't appreciate them enough.

Monday, August 24, 2009

Partners and Robbers

A jewelweed blossom is worth examining carefully; it is a little marvel of engineering, with a shape perfectly adapted to its pollinator, a plump bumblebee with a very long tongue and a thirst for nectar.

The shape of the little sac fits the body of the bumblebee like a glove; the side petals open like a pair of curtains to allow its entrance; the length of its spur, full of nectar is just right for the tongue of the bumblebee. And, finally and most important to the plant, the anthers (that carry the pollen) and the stigma (which receives the pollen) are placed so that the hairy back of the bumblebee rubs against them when entering the flower. The pollen is deposited on the bee and later on it is transported to other flowers.

For pollination to take place the bee has to enter the front of the flower otherwise it would fail to touch the parts of the flower that matter.

Despite this marvelous system, some very nice pollinators can turn into robbers and cheat the flowers that they usually serve diligently. This happens when the pollinator chooses to take a shortcut and bypass the well planned scheme of the flower. Such is the case of this bumblebee. When it takes nectar by slashing the spur from the outside it doesn't come near the pollen carrying organs and doesn't perform pollination.




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© Beatriz Moisset. 2012

National Pollinator Week

Pollinators are responsible for one third of the food we eat. Most fruits and vegetables have to be pollinated so that they can produce seeds. Also coffee, tea and chocolate need the services of pollinators.

We are so dependent on pollinators that we celebrate them once a year in National Pollinator Week, the last week of June.

© Beatriz Moisset