Year: 2010

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Sweat Bee Life

From the archives (upstate New York):

This summer I stumbled upon a sweat bee nest while moving some old boards. The nest was between two boards and this is what it looked like when I lifted the top one off. (Sweat bees, family Halictidae, are often metallic, shiny green or blue.)

Sweat bees vary from solitary to social. This nest had multiple adults, which probably indicates they were living socially. Does anyone recognize the species?

All life stages were present. In this cell there is a ball of food and what looks like an egg (it seems to have a knob at one end?). Usually the food is a mixture of pollen and nectar, hence the yellow-orange color.  See the water beads in the cell? The sweat bees line the cells with wax.

The older larvae are plump grubs. Prior to pupating, the larvae enter a resting stage called a prepupa.


Sweat bee pupae look like most bee pupae. You can see their eyes, mouthparts and antennae. This species does not appear to spin a cocoon.

Everything is pretty neat and tidy.

I tried to replace the board, but when I checked the next day, it was obvious the disturbance was too much. Many of the cells were empty.

The nest was overrun with snails (I think they ate the larval food),

millipedes, sowbugs,

and of course, ants.

What a difference a day makes in the life of a sweat bee.

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Ants and Peonies

From the photo archives:

You have probably heard all about the relationship of ants and peony flower buds.

Peonies (Paeonia sp.) are small perennial shrubs that produce large, lovely flowers in the spring.  The flower buds produce nectar via extrafloral nectaries, which attract ants. The ants chase off potential herbivores until the buds open. A simple story, yet an entire garden mythology has grown up around it. You can do an Internet search for “peony ants” and find a wealth of funny, and at times sad, myths.

But there may be another piece of the story that is rarely mentioned.

Do you know what this plant structure is? (Quit looking at the ant :-))

Since I already mentioned peonies, you can probably guess it is the fruit of a peony. Inside each of those three “pods” are rows of seeds completing development.

As this is not a bud, what is an ant doing there? Take a look at the next few photographs and see what you think.

Mandibles agape…

Do you see the fly?

Has anyone seen this before? Do you know if the extrafloral nectaries are still active? Are ants just poor botanists?

If you want to find out more, try:

B L Bentley. (1977). Extrafloral Nectaries and Protection by Pugnacious Bodyguards. Annual Review of Ecology and Systematics, Vol. 8: 407 -427.

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Ant of the Week: Weaver Ants

As you probably know, spiders and birds aren’t the only ones who know how to weave. Weaver ants (mostly ants of the genus Oecophylla) are named because the worker ants use silk produced by their larvae to sew or weave together leaves in trees to make a nest to live in.

Photo by Robin Klein at Wikimedia

To do this, worker ants form a living chain between nearby leaves in a tree and bring leaf edges together. Other workers carry the legless larvae to the edges and give them the signal to spit up silk. As the worker ants move the larvae back and forth, the leaves are bound together into a cluster. The ants use the leafy clusters as nests.

This video shows the workers in action.

Weaver ants are elegant, long-legged ants.

Photo source Sean.hoyland at Wikimedia

Some species of weaver ants are also known as green ants due to the greenish color of their rear sections (gasters). They are called citrus ants or orange ants because they are used to protect fruit in citrus orchards. Weaver ants guard their homes with vigor and attack and eat any arthropods in the vicinity.

Photograph by Axel Rouvin at Wikimedia

As far as is known, the ancient Chinese were the first to use these ants to control pests and protect crops. Around 1,700 years ago, farmers employed weaver ants to keep caterpillars, stink bugs and small rodents out of their valuable citrus orchards. Farmers could stroll down to their local market, buy ant nests full of ants and put them out into their orchards. Evidence suggests the farmers actually provided platforms or runways so the weaver ants could run from tree to tree.

So, that’s ancient history, right? Those were times before pesticides and modern technology. Who needs ants now?

In fact, in the later part of the twentieth century many growers did switch to using pesticides to protect their crops. Soon, because of the high costs of pesticides, and other problems associated with pesticide use, farmers quit using them and began using ants again in their orchards. Today farmers in Asia and Northern Australia rely on weaver ants to control pests of mango, coconut, oil palm and cashew orchards.

I would love to see weaver ants in real life someday. They are amazing.

Have you ever seen weaver ants in action?

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Related:

There is a children’s book that describes the ancient Chinese practice of using weaver ants in orchards called Ma Jiang & The Orange Ants by Barbara Ann Porte and illustrated by Annie Cannon.

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The Fire Ants Book

Related to the last post about Southern fire ants, have you seen The Fire Ants by Walter R. Tschinkel?

You would think that a book that is over 700 pages long about a single topic, and fire ants at that, would be pretty dreadful reading. Surprise! The Fire Ants has all the elements of a great literary work. It makes you laugh, it makes you cry. Walter Tschinkel turns out to be a scientist with a talent for writing far more than just straight research papers. As E.O. Wilson says in the Foreword, “He has delivered a masterpiece.”

I have been thinking about reviewing The Fire Ants for several months, but wasn’t sure how to tackle it because there is so much to discuss. It would be a huge post.

What would you think about taking a few chapters at a time and having a discussion? Any interest?

Let me know what you think.