THE GTPSY MOTH OX CRANBERRY BOGS. 11 
considered as a continuous record from 3.45 a. m. until 7.30 p. m. 
These observations determined that feeding began soon after day- 
light, gradually increasing as the temperature increased, until it 
reached its maximum from 9 to 11 a. m. when it began to diminish, 
reaching a minimum during the midday, then gradually increas- 
ing again, reaching its maximum from 3 to 5 p. m., and gradually 
decreasing after this hour, a majorh^ of the larvae seeking shelter 
on the underside of the leaves by 7 p. m. Wind dispersion records 
cited show practically no movement of small caterpillars between 
11 a. m. and 3 p. m., the period when there is practically no feeding 
and very little activity. 
INJURY BY A GIVEN NUMBER OF LARVJE. 
When a new cranberry bog is planted the vines are usually set in 
rows 12 inches apart, and the same distance in the row. The in- 
crease of the vine area is by runners radiating out from each plant, 
in all directions, eventually forming a dense mass of vines over the 
whole bog surface. From these runners upright shoots grow, and 
under normal conditions increase in height by growth from a ter- 
minal bud, and it is upon this new growth that the fruit is borne 
each season. It is evident that any injury to the terminal buds re- 
duces the amount of fruit in proportion to the number of buds de- 
stroyed. With the object in view of obtaining some definite infor- 
mation on this question an experiment was undertaken to determine 
the amount of damage to cranberry vines that would result from a 
heavy infestation of gipsy moths. Three pens were built 3 feet 
square, inside measurement, with sides 2| feet high. On the out- 
side of each pen, 6 inches from the top, four strips of board were 
attached at an angle of 30 degrees. Each pen was then forced into 
the bog about 6 inches and the sand firmly tamped both inside and 
outside of pens to prevent escape of larvae. On the underside of this 
overhang and 6 inches from the top on the inside of each pen bands 
of commercial sticky tree-banding material were applied in order to 
prevent the escape of larvae that were placed on the square yard of 
vines inclosed and to prevent other insects from gaining entrance to 
the pen. (PI. V, Fig. 1.) 
From year to year during the period covered by these studies 
varying numbers of first-stage larva? have been placed in these pens 
each season and the injury to the vines, as well as the feeding habits 
of the larvae on cranberry foliage, has been carefuly noted. 
The results of these experiments have shown that an infestation 
of two larvae to the square foot has destroyed nearly all the new 
growth of cranberry foliage. An infestation averaging one larva 
