50 BULLETIN 885, U. S. DEPARTMENT OF AGRICULTURE. 
over to the under surface of the leaf of the tree and only three had 
settled on the upper surface. On the two leaves that were tied to 
those on the tree a total of 65 larva? had settled. An equal number 
were dead attached to the eggs, apparently having died in the attempt 
to escape from them, because of the drying out of the leaves, as is 
shown later. A week later all the larva? that had migrated to the 1 
tree were dead. 
In order to show the effects of the drying out of the leaves on the 
hatching of the eggs the following experiments are of interest : 
EXPERIMENT NO. 1. 
On July 12, 1919, a shoot on which adults were clustered was brought to the 
laboratory. Fifteen spirals were laid on three upper leaves of the shoot and 
ten on two lower ones. The shoot was placed in a bottle of water for observa- 
tion. 
In the 15 spirals were 387 eggs. In the 10 spirals were 187 eggs. 
On July 23, 1919, the entire shoot was wilted, the upper leaves were not dry, 
but the lower ones were turning brown and drying out. These leaves were i' 
removed and put in covered petri dishes for observation. 
On July 26, 1919, 340 out of the 387 eggs hatched (approximately 90 per cent), 
but only 30 of the 187 eggs had hatched on July 30 and the experiment was 
discontinued. 
EXPERIMENT NO. 2. 
Eggs on leaves brought into laboratory from the field July % 23, 1919, still 
whitish in color, hence not over 24 hours old. Put in covered petri dish. 
Number of eggs, 71. 
July 26— Eggs fully colored. 
July 28 — Leaves drying out. 
August 1 — 'Leaves thoroughly dry, eggs shriveled. Discarded. 
EXPERIMENT NO. 3. 
Eggs on leaves brought into laboratory from the field July 23, 1919; blackish 
in color, indicating that they were over 8 days old. Put in covered petri dish. 
Number of eggs, 335. £" 
July 26— Eggs shriveling. Leaves wilted but moist. 
July 28 — Leaves drying out; no hatching. 
August 1 — Eggs shriveled. Leaves slightly moist. Discarded. 
EXPERIMENT NO. 4. 
Eggs on leaves brought into laboratory fr.,m field July 23, 1919; eggs dark 
brown in color, indicating that they were at least 3 days old and not more than 
10 days old. Number of eggs, 173. 
July 26 — No hatching. Leaves wilted but moist. 
July 28— No hatching. Leaves drying out. 
August 1 — Eight larvae died in emerging. Rest of eggs shriveled. 
Leaves slightly moist. Discarded. 
EXPERIMENT NO. 5. 
Eggs on leaves brought into laboratory from field July 23, 1919; eggs brown 
in color, indicating that they were over 3 days old. Number of eggs, 141. 
July 26 — No hatching. Leaves wilted but very moist. 
July 28 — No hatching. Leaves drying out. 
August 1 — No hatching. Eggs shriveled. Leaves still slightly moist. 
Discarded. 
* 
