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With a life's experience of teaching field studies in the Forest of Dean, Brian Cave explores the ecology of rural France. More Info

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An English Naturalist in France

Ants with yellow spots

June 14, 2015

walnut aphids and antswebsite statistics

 

The  ants fall from the walnut tree onto the table below.  They are all so small that you cannot make out any detailed structure.  Under the binocular microscope that is more easy – But, sad to say,  you can only see any structures by killing them first.  That i do by putting them in the freezer for a short while.

To the left is a picture of two species.  To the naked eye they look identical.

But with the magnification there are striking differences.  The one named Dolichoderus quadripunctatus is the most interesting because it could be fairly rare.  I will call it the four spot ant because on the abdomen are four yellowish spots. You can clearly see one, another is in the shade but just visible . the two other on the other side of the body.  The other ant is a worker ‘black ant’ . It is a very common ant.  One other easily visible difference is in the structure of the ‘petiole’ between abdomen and thorax. The black ant has a spiky growth there which is more like a rounded bump in the 4-spot species.

The books inform me that the 4-spot is the only ant in France which is decorated in this manner.    Searching for more information I find that it is only ‘probably’ found in two departments of the country and the Lot(46) is not one of them.  It certainly is in the Lot.

I do wonder what the function of the four spots might be, or are they just chance markings?   Do they indicate to other workers of the same species that they are ‘associates’ and thus when they approach the nest they can be accepted?  Then one might ask – are the wandering black ants beaten off?  Is it as simple as that?

Top right is a picture of two 4-spot ants nursing aphids on walnut leaves.  They do this to collect the sugary juice which the aphids excrete.

by Brian Cave. Find out more about Brian Cave here.

Categories: Ants, Trees