Prociphilus fraxinifolii (Riley).

Prociphilus fraxinifolii differs from typical Prociphilus species in the nature of the individuals composing the various generations. The following observation was made by the senior author at Longmont, Colorado, in 1925.

A young white ash tree in one of the city parks was very heavily infested with Proc. fraxinifolii on June 18. At this time many first instar lice were travelling from the infested tips of the branches toward the trunk of the tree. Upon reaching the trunk, these young lice travelled up or down until another branch was reached, when they started toward its tip. It was thought that the migrating lice might be in search of fresh leaves upon which to locate.

At the time of observation some curled leaves contained stem mothers and many large mature apterous females which were giving birth to the young already mentioned. Others contained only a limited number of these young.

A cluster of curled leaves containing the stem mothers and apterous females was removed and fastened to a branch of a young ash tree that had no curled leaves. Immediately . the young were observed travelling toward the trunk of the tree. The second day after the curled leaves were placed on the young tree, the leaves of nearly every branch below the point where the curled leaves were attached were badly curled.

On the fourth day no leaves above the point where the curled leaves were attached to the branch were curled. The migration of young, therefore, appears to be mainly downward. The third and fourth day after the curled leaves were placed on the young tree they were completely dry and the mature lice in them were dead. Apparently the stem mothers and second generation apterous females do not migrate.

This observation indicates that the sequence of generations of Proc. fraxinifolii is somewhat similar to that of Eriosoma species. No winged individuals were secured. It is believed that the winged lice are produced by the migrating generation (the young of the second generation), and, therefore, belong to the fourth generation.

- Asa Maxson, George Knowlton: (1929) The tribe Pemphigini (Aphididae) in Utah^©