I would say that my feelings about ants are very mixed at the moment.
|photo credit: williamcho|
As an Entomologist, I’m absolutely fascinated by ants. Who wouldn’t be fascinated by these tiny insects that form amazingly complex and efficient societies that parallel those of humans?
Millions of Ants
We often think of ourselves as the most intelligent or civilized but I think ants can give us a run for our money! Their ability to cooperate with each other, to build nests, care for their young, exploit and manipulate resources of all kinds and defend themselves in many different ways have made them so successful that we often butt heads. We are struggling to keep the upper hand in agricultural and urban situations. They can be quite a nuisance, but one can’t help being intrigued!
Ants share the order Hymenoptera with bees and wasps, some of which also live in social groups. Ant colonies can range from a few dozen to millions of individuals, but unlike bees and wasps, there is no such thing as a solitary ant. Many form permanent nests while others are nomadic. Most are predators or scavengers, while some grow their own food. Some even farm and “milk” other insects like we do with cattle.
Ant colonies typically consist of a queen (occasionally many), the only member of the colony to reproduce, and her sterile daughters or workers. Each year, new reproductive females and males, called drones, are produced. The winged males and females leave the colony to mate and start new colonies. The males die immediately after mating and the females shed their wings and become queens of their own colonies. Some colonies do not even have queens, only reproductive workers called gamergates. Some ant queens can live for up to 30 years, placing them high among the longest lived insects.
If the queen is the heart of the colony, the workers are the blood. She produces them, they develop into adults and they take care of every aspect of the colony. Their responsibilities range from tending to the queen, the young, the nest and each other, to foraging for food or building materials and protecting the nest. The younger ants can be founding tending to the inner workings of the nest while the older ones, who are more expendable, have the more hazardous task of foraging.
Workers can be different sizes, but the largest are the soldiers (remember, all are female!). Soldiers are strong, brave, and often have sizable mandibles! Any worker ant will sacrifice itself for the good of the colony. Who do you think invented suicide missions? This selfless devotion and ability to work together as one unified organism is what has made them so successful. There are so many ants that they make up an estimated 20% of the terrestrial biomass on earth. That number far surpasses that of vertebrates!
We have several types of ants here at the Cockrell Butterfly Center, some captive, and some, well, not so captive. A facility such as ours is a haven for pest species including cockroaches, fruit flies, and lots and lots of ants. We’ve always had ants in the conservatory. The conditions are favorable and the food, including fallen butterflies, is plentiful. In the conservatory, they are manageable and they don’t really bother anyone.
Of over 12,000 described species of ants, only about 20 species are considered “pests” – i.e., they mess with humans or our possessions in some way. The pest species are mostly very small ants including sugar ants, ghost ants, pavement ants, and others, that sometimes get into our houses and larders. Unfortunately one of our uninvited residents is perhaps the hardest species of household pest ants to control, crazy ants.
|photo credit: zayzayem|
Crazy ants, also known as longhorn crazy ants (Paratrechina longichornis) have earned their common name from their erratic and “crazy” movements. They move extremely quickly and in all different directions. They do not form foraging trails like most other ants, instead, they will go straight towards a food source, then meander all over the place back to their nest, making their actual nest very difficult to find!
Crazy ants feed on a wide variety of things including live or dead insects, fruits, nectar, honeydew (a secretion from hemipteran insects), and many household foods. The best way to control these ants is exclusion, or keeping them out and keeping food and water sources out of the area.
Crazy ants are very easily identified. They are small, dark colored ants with very long antennae. They are monomorphic, meaning all of the workers look the same and are the same size. They do not sting but they can be present in such great numbers that they can be quite a nuisance. We’re currently doing everything we can to combat them!
New Leaf Cutter Ant Colonies!
Luckily, there are also ants that we are glad to have. After losing our tropical leaf cutter ant colonies in 2010, we have been blessed with 3 new colonies of Texas Leaf cutter ants (Atta texana).
I bet you didn’t know that leaf cutter ants are native to Texas! Leaf cutter ants are very fascinating and fun to watch! The workers use their powerful jaws to cut pieces of about 200 different types of leaves. They do not eat the leaves but carry them back to the nest. Once there, they chew them into a mulch that they use to grow a special type of fungus. The fungus is what the ant larvae feed on, so they are true fungus farmers!
Leaf cutter workers are polymorphic, meaning the workers differ in size and appearance. The smallest workers, called minims, are meant to tend to the fungus garden, queen, and brood. The minor workers, which are a bit bigger, patrol the nest and are the first line of defense. Mediae are larger workers with strong mandibles that forage, cut leaves and bring them back to the nest. The largest are the major workers. They act as the soldiers and are often very large with big strong mandibles that can break the skin. I know this from experience!
Leaf cutter ants also do not posses a stinger, but they sure do bite and will not let go! The mutualistic relationship between the ants and the fungus is quite incredible. The fungus must be actively maintained and cultivated by the ants. It constantly needs new fresh leaves to grow and survive. The ant larvae feed exclusively on the fungus and need it in order for them and the colony to survive. The ants constantly monitor the fungus to see if any leaves are toxic or if any other competing fungus is growing. They will destroy any other fungi with a bacterium that grows on their skin and secretes antimicrobial chemicals. WOW!
Two of our new colonies came from the University of Texas, which was so generous to donate them to us! When we got them I noticed that the fungus gardens, which are usually green, were all white. These ants had been fed on oats instead of leaves, which they can apparently manipulate in the same manner. It’s really cool, they look like some formations you would find in a cave. One of these colonies will soon be on display for everyone to watch as they busily carry leaf fragments to their gardens.
There are so many interesting things about ants. They really are diverse and fascinating. I encourage you to read up on them a little bit; even just by clicking the links in this blog, you may find out things you would have never expected!
Next time you see ants trailing in your house or outdoors, don’t think of them as just a nuisance, think of how incredible they are and how hard they work. You may have a newfound respect for the little critters.
Until next time, happy bug watching!