Study of the Structure of an Allegheny Mound Ant Mound.

By Piers MacNaughton and Ian Maclellan

Purpose

Allegheny Mound Ants have a negative effect on vegetation in their area as a result of their formic acid. They pose as a threat to many agricultural communities. (UMaine)

By understanding the structure of their mounds, a method to destroy their mounds and to control their population may be discovered.

General Information

Feed on sap-sucking aphids and insects. (UMaine) Clear the area around their mounds from vegetation

with their formic acid. (UMaine) At a similar latitude to our study cite (Michigan), half

of the colonies had early stages of broods during the month of May. (Bristow)

In a mound our size there are approx. 4,000 ants. (UMaine

Introduction to Mound Structure

The majority of the tunnels and galleries are located in the top foot of the nest and decrease in frequency at lower levels. (Bristow)

The mound serves as a solar receptor to attract heat from the sun. (Bristow)

The temperature of the nest is hottest near the surface, but the lower depths are used for storing the larvae. This may be the result of a managed microclimate. (Bristow)

Case Study

42 inches diameter 15 inches from top of

the mound to ground 12 inches from ground

to bedrock. No living trees in 10 ft

radius Sparse low growth

Case Study (Continued)

1 hour and 15 minute excavation Shoveled from the top until we reached the bedrock. Girded perimeter a

meter from base of

mound 8 inches

deep to check

for underground

connectivity.

Case Study (Film)

First Half: Density of ants on the bedrock. Drones found only deep down in the mound.

Second Half: Mound built over a fallen log. The log was tunneled through, and formed part of the structure.

Shortcut to Ecologyants2.mov

Observations

Ants congregated most densely on the bottom of the mound. Bristow’s study predicts that the disturbance brought about by digging doesn’t cause this

Our two trenches didn’t reveal any ant tunnels between mounds. This may indicate above ground connectivity. The shoveling may have caused tunnels to collapse and not be visible.

Ants were observed far away from their mound, but this could be for foraging or connectivity purposes.

Ants were observed climbing on dead trees

Ant Farm Set Up

Two storm windows placed 1 inch apart. Layers of sand and flower pot soil were added to a height

of about 8 inches. Preliminary batch of ants contained approx. 75 ants with

no soil. Secondary batch contained approx. 500, including several

drones. They were fed honey (2 ml. a day), various insects, and

pieces of bagel. Water added through the top liberally.

Ant Farm Set up

Ant Farm Observations

Not enough protein content to keep ants alive. First batch lived approx. 3 days.

Secondary batch had redistributed 4 inch top soil that had been collected on site, and began tunneling into other layers of soil, about 4 inches deeper. Some ants are still alive, probably eating the dead ants for protein.

Ants convened at the farthest reach of each tunnel.

Discussion and Conclusion

The frequency of their tunneling decreases the deeper they go since the surface of their mound collects the most heat, but the broods, larvae and drones are contained at deeper levels.

Thus a method of destroying the mounds would have to penetrate to the core of the mounds to sever the reproductive cycle.

Discussion and Conclusions (Cont.)

The ant farm showed that the ants made it their primary goal to establish a network of tunnels.

This microhabitat simulation showed the importance of shelter for the ants. Their mounds are necessary for breeding, food distribution, temperature control, and protection.

Sources Cited

Bristow, C. M., D. Cappaert, N. J. Campbell, and A. Heise. 1992. Nest structure and colony cycle of the Allegheny mound ant, Formica exsectoides Forel (Hymenoptera: Formicidae). Ins. Soc. 39:385-402.

Choate, B.A., F. Drummond, and D.E. Yarborough. 2008. Wild Blueberry Fact Sheet, Sheet no. 195. The University of Maine, Orono, ME 04469.

Special thanks to L.A. Creech for filming our excavation