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Indiana University Studies 
(June 25 acc. Triggerson, June 28 at Toronto acc. Brodie 
coll.), reaching full development in August (August 17 in 
northern Indiana in 1927) or early September (mid-September 
in southern Indiana). When the hypertrophied tissue first 
pushes thru the slightly ruptured epidermis of the leaf, the 
embryos, according to Triggerson, “measured 125^.-130^. 
In galls gathered on the first and second of July, larva were 
found measuring 374^. These were similar to the young 
larva which give rise to the sexual form, having a slightly 
depressed head, sharp pointed mandibles, broad, prominent 
thorax, and pointed, reflexed abdomen. During the summer, 
molts were observed after which the larva measured 500 
750 ^., 1% mm., 1% mm., 2% mm., respectively, thus show- 
ing five stages during the life-history. . . .” From about 
the middle of August “the thorax does not show a great in- 
crease in size, but the abdomen loses its reflexed character, 
becomes globose, and increases in size until pupation.” Trig- 
gerson obtained the first pupae on the 5th of September. 
Weld found pupae on September 8 (1906), near Chicago. 
The galls fall with the leaves to the ground late in September 
or October, or some of them remain with the leaves on the 
trees. Transformation probably occurs soon after pupation, 
but emergence of the adult does not ordinarily occur until 
some time after that. For breeding purposes, the galls are 
best left on the trees until just before the adults are due to 
emerge. 
Our records for emergence range from early in October to 
early in January, with the bulk of the adults coming out in 
November. Actual dates from published records, Museum col- 
lections, and my own breedings are October 3, 7, 10, and 31 ; 
November 1, 5, 7, 12, 13, 15, 16, 18, 20, 22, 26, and 27; De- 
cember 1, 4, 5, 8, 10, 12, 14, 16, 17, 20, 21, 22, 23, 25, and 28; 
and January 1 and 3. In spite of these widely distributed 
dates, most of the emergence occurs late in November and 
early in December. I have not been able to discover any 
correlation in these records between the latitude of the locality 
and the time of emergence of this insect. 
Triggerson’s designation of November 5 to 21 and rarely in 
early December for the emergence of erinacei is evidently 
based on a single season’s observations in a single locality. 
The emerged insects, according to Triggerson, “are most active 
on cold days or early in the morning. During the warm 
