Formica Pupae: Cocoons or Not?

Tipping over rocks can lead to interesting discoveries.

On a recent trip to western New York, I tipped over a rock.


I found a colony of ants in the Formica fusca group. (They looked silvery, so possibly Formica subsericea, but my eyes are getting older.)

The worker ants scurried to remove the brood to safety.

Something else caught my attention. Do you see it?

Maybe it will be clearer here. Notice the workers are rushing to hide the pupae.

The cocoon on the left is probably a reproductive pupa (queen or male). It is larger than the workers and the cocoon is made of darker, coarser silk.

The cocoons on the right are worker pupae. They are the same size or smaller than the workers and made of lighter silk.

What’s up with the white, naked pupa in the center?

It is the size of a worker. Conventional wisdom says whether or not a larva spins a cocoon before pupating is species specific. Why doesn’t this one have a cocoon like the others?

Some suggestions:

1. Wallis (1960) and others have proposed that Formica fusca larvae must be covered with bits of debris before they can spin a cocoon. Perhaps this one wasn’t buried properly and failed to spin?

2. Perhaps it isn’t a Formica fusca pupa.

Colonies in the Formica fusca group are frequently parasitized or enslaved by other species. This video shows a mixed colony of Formica sanguinea and Formica fusca with a bare pupa.

I didn’t see any evidence of Formica sanguinea workers in the colony I photographed, though.

Have you ever seen Formica pupae without cocoons? If so, why don’t they all have cocoons? What might be the advantages and disadvantages of spinning a cocoon versus not?

References:

I. Wallis, D. (1960). Spinning movements in the larvae of the ant, Formica fusca. Insectes Sociaux. 7: 187-199. 10.1007/BF02224080.

See previous post about Formica fusca group ants.

So You Want to Find a Queen Ant

A very popular question this time of year is, “How do I find an ant queen?”

As with many things, finding an ant queen requires work, patience and sometimes a bit of good luck.

1. The very first step is to make sure you can identify an ant queen from a worker ant when you see one.

(Note:  the middle section in ants is not technically a thorax as it is called in other insects, but is now called a “mesosoma.” Alex Wild in his article at Myrmecos calls it a thorax to avoid confusing beginners, I believe. I originally used an older term “trunk” in some of the figures.)

camponotus-pennsylvanicus-queenThis carpenter ant queen formed a small chamber under the loose bark of a log.

2. You also need to understand the colony cycle in ants.

There are many variations, but in general the colony is founded by a single queen or group of queens. The queen(s) lay eggs that hatch into larvae. Once the larvae are mature, they pupate, sometimes within cocoons (See eggs versus pupae ). The first adults to emerge will be the wingless worker ants.

ant-life-cycle

When the colony conditions are right, the queen lays some eggs that will become new queens and males. The adults will have wings. They are called “alates.”

Camponotus-pennsylvanicus-3-alatesAlex Wild calls the females with wings that have not gone on their mating or nuptial flight “princesses.”  They may stay in the nest for weeks until conditions are just right.

When the winged ants are flying out of the nest in order to mate and start new colonies, it can be called “swarming,” the “nuptial flight” or simply “mating flight.” Unfortunately swarming is also used to describe mass movements of ants, so it can be a confusing word. Generally the workers ants are rushing about in great numbers protecting the emerging males and princesses as they prepare to fly off.

Nuptial flights or swarms of ants

Once they have mated, the “princesses” generally pull off their wings and are ready to start new colonies. This is an optimal time to find new wingless queen ants.

3. Next, learn something about what kind of ants you might find in your area. If you have one or two species in mind (I would recommend larger-sized ants that don’t sting for a first ant farm), then you can look up when queens are likely to be active in your area.

How do you do find out what kinds of ants are in your area? One place to start is AntWeb, which has ants identified by region. See that tab at the top of this page that says Ant-Related Websites, Forums and Blogs? There are a number of blogs that specialize on ants in a given region. (Please let me know if you have one to add.)  You can also search the ant forums by the name of your state or country for more information. You might consider joining an ant forum or social media group to learn more about the hobby, as well.

4. In general, ants tend to swarm associated with certain environmental conditions such as temperature, humidity, time of day, and precipitation. For example, in New England, you can be sure to find carpenter ant queens running on the ground the morning after the first spring thundershowers, likely in May. Here in the Southwest, harvester ants swarm after the summer rains in July called monsoons. Learn what conditions the ants you are looking for prefer and watch the weather!

Swarming in winter ants at Myrmecos

More about ant queens and new colonies

5. Finally, nothing beats getting outside and searching around (just be sure you have permission to collect where you search.) Look under stones, sticks or near where lights are left on all night. I found some queens near tennis courts, which have bright lights on at night. Others have found queens that have fallen into pools. Good luck!

You also might be interested in:

Beginners Guide to Ant Keeping

Does anyone have anything to add?

What Does A Queen Ant Look Like?

Do I have an ant queen? What does an ant queen look like?

Because I frequently am asked these questions by beginning ant enthusiasts, let’s go over what you need to look for to tell if the ant you have seen or captured is a queen.

(Note:  this guide is for ants with a morphologically distinct queen. Not all ant species have distinct queens.)

If you encounter an ant swarm like this one, you can probably spot the virgin queens right away. They are the big ones with the wings.

Remember the part about the wings. Only males and virgin queens have wings, but even after they lose their wings the queens will have signs they once had them.

This is a queen. I can tell because her midsection, or trunk, edit:  now called mesosoma, is a wide as her head. It is large because it contains all the big muscles she needs for flight. This queen has been on her mating flight and has lost her wings.

From the front view, you can see her trunk mesosoma is as wide as her head and that there are scars on the sides where the wings were.

Here’s a top view. See how wide she is? A worker ant would be narrower.

This is a queen fire ant without wings.

See how large her trunk mesosoma is?

Here comes the quiz. Is the following ant a queen?

It has wings and a huge trunk mesosoma. Is it a queen?

I can tell by the small size of the head that it is a male. Males also fly, so they also have big flight muscles.

As you become more experienced, will become fairly easy to tell whether any ant you encounter is a queen.

Using what you have learned, is this a queen?

Perils of Swarming

Right on cue the Solenopsis xyloni have been swarming in Phoenix.

At eight in the morning, the new queens are climbing up grass stalks and leaves.

Any idea why the worker ants are standing on and huddled around the queens?

I’ll give you a hint.

You might be able to spot two of the reasons near the center line in this blurry photograph.

I’m afraid this is the best shot I got of the aerial assault by phorid flies.

Phorid flies of the genus Pseudacteon are known to attack fire ants. They are commonly called ant-decapitating flies for the fact that the infested ant’s head falls off during the final stages of the fly’s development. Each fly lays her eggs into the adult ants. The fly larva hatches from the egg, and feeds within the ant’s alitrunk. Once the larva is ready to pupate, the ant dies and literally loses its head. The larva pupates in the cozy head, and eventually emerges as an adult fly to attack more fire ants.

Photograph from Wikimedia

There was a small cloud of the flies attracted to the activity of the ants. These phorids seemed to particularly target the reproductives, although other phorids I have read about target workers.

To give you an idea how small and fast these flies are, check the area around the beige leaf in the lower right corner of the second part of this video.

Have you ever seen phorid flies around swarming ants? If so, what species of ants?