Category: Bug of the Week (Page 200 of 218)

Bug of the Week: Ants Visiting Extrafloral Nectaries

It is cold (for us) and windy this morning, and I wasn’t sure I’d be able to find a bug of the week. No fear, there’s always something going on in the insect world.

barrel cactus

First I checked our barrel cactus, which is covered with yellow fruit.

barrel cactus

As I got closer, I spotted a beige patch near the base of one of the fruit towards the right/center of the photograph. You’ll be able to see it more clearly in the next photograph.

cactus

The biege patch looked soft and furry, with some yellow and orangish bumps.

ants at extrafloral nectaries

Ants were visiting those bumps in a purposeful way. First they would arrive looking slender.

ants at extrafloral nectaries

After spending some time with their heads near the bumps their hind portion, called a gaster in ants, would start to swell up.

ants at extrafloral nectaries

These ants are feeding at the extrafloral nectaries of the cactus. Nectaries are parts of a plant that produce the sweet juicy nectar. Many are found inside the flower of the plant. These structures are called extrafloral because they are outside of the flower.

Why does a cactus supply liquid sweets in the form of nectar to ants, especially in the desert where water is in short supply? There are several theories, including that ants increase the fertility of the soil around their mounds and ants are more likely to nest nearby when food is available, and/or that ants feed on insect pests while on the cactus. In any case, it is a fascinating example of just one of the complex relationships between ants and plants.

Thinking of sweets makes me want to have a cup of hot chocolate…

Ant Mandibles

A question just came in about what ant mandibles look like. Now this might not be something you think about every day, but it really is an interesting topic. I remembered a wonderful website that discusses all the things that ants do with their mandibles and shows some fantastic close up photographs of different species. I do have to warn you, however, it is written for adult scientists. The site is called Diversity of Ant Mandibles.

For a more child-friendly general discussionof insect mouthparts, check my recent post on the topic.

Bug of the Week: Fruit Fly

Carrying along the theme of insects that have changed the course of human history, let’s look at another species with humble beginnings and a big role. Here is a celebrity that can be found in the fallen, rotting grapefruit in my backyard.

fruit fly

This photograph is of a male fruit fly, Drosophila melanogaster. Notice the bright red eyes. I can tell the one in the middle is a male because the end of the abdomen is dark. You might recognize these little flies if you have ever taken a genetics class or left a banana out on the counter too long.

fruit fly

These are female fruit flies. Their abdomen lack the black block at the end.

Also called vinegar flies or pomace flies, these tiny creatures don’t actually feed on fruit, but their larvae feed on the fungi associated with decay. A sound, healthy fruit is of no interest to a fruit fly.

As for their benefit to humans, fruit flies have been the staples of biology labs for over a century. Much of what we know about genetics and developmental biology came from studies of fruit flies.

Drosophila melanogaster was not native to North America, but is now almost a domesticated species. It is found wherever people are found. In the western United States we have a few native species, including another fruit fly used in biology labs called Drosophilia pseudoobscura.

If you are interested in learning more about fruit flies, try the quirky adult nonfiction
book Fly: The Unsung Hero of Twentieth Century Science by Martin Brookes (Be aware that this book contains what would be considered adult themes.)

For kids, you might try a cute fiction picture book about flies, called
Diary of a Fly by Doreen Cronin, Harry Bliss (Illustrator). My son got to meet the author and illustrator of this book at a local indie bookstore, and they were a wonderful team. The illustrator had a big impact on my son, who loves to draw.

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