Swarming Season Arrives in The Sonoran Desert

Solenopsis xyloni reproductive prepares to fly.

William Morton Wheeler had this to say about swarming in Ants: Their Structure Development and Behavior (1910) page 183:

“When the hour for the nuptial flight grows near, a strange excitement pervades the ranks of the workers. At such times even the blind and etiolated workers of the hypogaeic species venture out into the sunlight and accompany the males and females to the entrance of the nest. The winged forms move about in tremulous indecision, but, finally venture forth, run about on the stones or climb about on the grass-blades till they have filled their tracheae with a plentiful supply of oxygen. Then they spread their wings and are soon lost to view high in the air.”

A Rainbow of Ant Larvae

On a recent trip to Colorado, I got to spend a few hours in the Rocky Mountains at about 7500 feet. It was an ant lovers paradise. Virtually ever stone I flipped had a colony of ants under it. I found six different species in no time flat.

Although I tried to disturb them as little as possible, I was struck by the range of sizes, shapes and colors of the larvae, so I did manage to snap a few photographs.

The larvae in this case were white. Do you see the egg stack next to the larva at the bottom towards the middle? I’m pretty sure that one is about to have a snack.

Under a nearby rock, some of the larvae and pupae were bright yellow.

These were orange. In contrast, the eggs on the left are the usual white.

This was a different nest, but the larvae are the same orange color.

It was fascinating to see so many colors of larvae in one place. Wish I could have spent a couple of days there.

This is the view those ants have 🙂

Can ant larvae get too cold or hot?

Mike wrote to the “Consult-Ant” with a number of questions about ants. I am going to try to answer each one in a separate post. For the original list of questions and links to all answers, visit here.

10)  If the eggs, larvae, and pupae were placed in bad conditions, specifically temperature, for a short period of time, would they be harmed?

As you might expect, the optimal temperature for rearing larvae depends on the ant species. In his 1988 paper, Porter found that fire ant larvae (Solenopsis invicta) grew and developed between 24° C and 36° C, with optimal growth at 32 °C. Abril et al. found a range of 18°C to 32°C for larvae of the Argentine ant, Linepithema humile, with optimal development closer to 26°C. Argentine ant larvae held at temperatures above 32°C did not survive.

Of course if the temperatures are hot enough to burn or cold enough to freeze, then the larvae would be harmed even with brief exposures. But what about temperatures that are not extremely hot or cold, but just outside of the range for normal development? Once again, depending on the species, there could be critical windows of development that can be missed if the larvae aren’t reared at proper temperatures. Exposure to low temperatures could potentially stimulate larvae to enter diapause, as well.

Adult worker ants are much less susceptible to changes in temperature. Types of desert worker ants may survive soil surface temperatures of 60 to even 70° C! (Marsh 1985)


In an actual nest, the nurse workers move the larvae from chamber to chamber to ensure the larvae are exposed to the correct temperatures.

Let me know if you have more specific questions.


Abril S, Oliveras J, Gómez C. 2010. Effect of temperature on the development and survival of the Argentine ant, Linepithema humile. Journal of Insect Science 10:97 available online: insectscience.org/10.97

Marsh, A.C. (1985). Thermal Responses and Temperature Tolerance in a Diurnal Desert Ant, Ocymyrmex barbiger. Physiological Zoology, Vol. 58, No. 6 (Nov. – Dec., 1985), pp. 629-636.

Porter SD. 1988. Impact of temperature on colony growth and developmental rates of the ant, Solenopsis invicta. Journal of Insect Physiology, 34(12): 1127-1133.

Ant Eggs Versus Pupae


Sorry I could not find the question box, but me and my cousin were digging through a ant hole and we found ant eggs. What do they need to grow? Sunlight, coldness, what kind of environment can they live in?


Dear Alexis,

The first question I have for you is: did you collect ant eggs or ant pupae? The second question is:  did you collect worker ants too?

Ant eggs are tiny (much smaller than worker ants), white, shiny and oval.


You can see a pile of ant eggs in this photograph in the middle and a little to the left.

Ant pupae are as large or even larger than worker ants and often have a beige silken sac around them.


They also have a black dot at the end.

If you have eggs, then you will really need worker ants to take care of them. The larvae that hatch from the eggs will need workers to feed them, clean them etc. The larvae are helpless.  I have a post about ant larvae, if you’d like to learn more. And just so you know, there is a chance the workers will eat the eggs.

If you have pupae, they could become worker ants. Again, they will do better if there are some worker ants to take care of them. Without a queen, they will not live as long as they would in nature.

In their nest under the ground, the ants normally grow up in dark, moist and relatively moderate temperatures.

I am glad you are interested in ants. Let me know whether you have eggs or pupae.

(Note: As I mentioned previously, I have been the “Consult-Ant” on the Leaping from the Box website. I answer questions about ants and ant farms. From now on I will post the answers here, and when Karen has time she will also post the answers on her site.)