Lire History oF AN Oak Twic GIRDLER 19 
Fig. 4, Plate 1. The following year, therefore, this larger branch would 
die. One such branch measured an inch and a half in diameter and 
was eight and a half feet long. 
PupaE. By May 1 of the second year following egg laying the 
larvae were found in the prepupal position. By June 1 practically all 
found were pupae. 
As this life history seems rather unusual, the notes of 1914, 1915 
and 1916 were supplemented by notes for 1917 and 1918. In August 
and September, 1918, many red oak trees again showed signs of serious 
infestation and hence the life history as given is certainly correct for 
this part of Minnesota. 
PARASITES 
Parasitism on the larvae of the species was quite evident. At ten 
different times, the first time just a year after egg laying, parasitic 
hymenopterous larvae and later, pupae were taken in the burrows of 
the twig girdler. The reared adults sent to Mr. S. A. Rohwer of the 
U.S. Bureau of Entomology proved to be a new species of the genus 
Tetrastichus. 
CONTROL 
Obviously this twig girdler is a difficult insect to combat. The only 
possible control on large shade trees would be to trim all small dead 
branches from the trees and burn them with their insect contents. The 
odd or second year of the infestation these dead twigs stand out very 
prominently over the tree and can easily be cut. The labor expense, 
however, in such a project is practically prohibitive. Twenty-five hours 
were required to prune one red oak, five feet three inches in circum- 
ference, thirty-nine feet high, and with a spread of thirty-four feet. 
The work on this tree was done so successfully that in the next infes- 
tation year it was not nearly so badly damaged as others in the neigh- 
borhood. To be really effective, all the affected trees in the neighbor- 
hood should be pruned. It is possible also that spraying the trees with 
bordeaux mixture or lime sulphur would act as a preventive as in the 
experiments with A. bilineatus. In any case it is a community problem. 
