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08-12-04
What Would a Picnic be Without
Ants?
Summer is the season for picnics. Picnics are defined as pleasure parties
with food provided by the participants. Generally, a lot of food! Officially,
picnics are held outdoors.
There are many kinds of picnics. Picnics come in all shapes and sizes.
Some are sponsored by companies, political parties or service organizations.
These picnics are frequently adorned with banners and accompanied by speeches
and photo ops. Other picnics are family reunions where distant cousins
get reacquainted or meet for the first time. Still other picnics are private
affairs with one family and a picnic basket packed with goodies.
So popular is the idea of a picnic that we even have special tables just
for such things. Parks have shelters and provide outdoor grills for cooking
to accommodate picnic groups.
Regardless of the type or location of the event, one thing that all picnics
have in common is that insects will show up to pester the human participants.
Flies and yellow jackets buzz around, picnic beetles land in the salad,
mosquitoes look to extract a blood meal from the human participants and
ants march across the table.
Ants are so common at picnics that some fabric designers have even included
ant images on the red-and-white checkered fabric that has come to symbolize
picnic tablecloths.
Ants are a very common and widespread group of insects. They are, in
the opinion of many entomologists, the most successful of all insect groups.
As individuals, ants probably outnumber all other animals in terrestrial
habitats.
All ants are social insects that live in colonies in nests. This means
that individual ants must leave the nest and collect food for the colony.
Food habits of ants vary widely. Some ants are carnivores that feed on
living animals. In this case, the food is frequently of the insect type,
including other ants. Some ants are herbivores and feed on plant material.
Still others are omnivores and feed on a combination of plant and animal
food.
So why do ants show up at our picnics? The same reason that humans show
up -- food!
But how do ants find the picnic? It works this way. Certain worker ants
in the colony are foragers. This means the ants leave the nest in search
of food. In order to find their way back to the nest, the foragers will
mark the path with a chemical called formic acid. The foragers just wander
around until they encounter a food source. Then, they haul some of the
food back to the nest. This is accomplished by carrying a piece in their
mandibles or swallowing a morsel. The latter approach requires that the
ants regurgitate when they get back to the nest. Either way, workers are
recruited to help bring the food home.
hen ants find a good food source, they quickly bring others to the location
to harvest the food. It is the ant equivalent of the saying, "Making hay
while the sun shines." Each ant that goes to the food source remarks the
trail. So the trail to the food is constantly trod by worker ants on their
way to the food or coming back to the nest.
The trail will not always be the most direct route from the nest to the
food. The trail reflects the path the first worker took as she was searching
for a food source. But each of the ants will follow the same trail. It
would appear that ants are wasting energy by not taking the most direct
route to the food source.
So what if ants aren't as efficient as we sometimes make them out to
be? If ants are headed to a picnic, the scenic route might be preferred.
After all, it is the atmosphere that makes a picnic fun. There are more
efficient ways to have a meal.
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