UNITED STATES DEPARTMENT OF AGRICULTURE 
» BULLETIN No. 273 
w - - — •* 
Contribution from the Bureau of Entomology 
L. O. HOWARD, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
August 24, 1915. 
DISPERSION OF GIPSY-MOTH LAKVM BY THE 
WIND. 1 
By C. W. Collins, 
Entomological Assistant, Gipsy Moth and Brown-tail Moth Investigations. 
CONTENTS. 
Previous investigations: Page. 
On dispersion 2 
Of hairs on small larvae 3 
Studies of acuminate and vesicular hairs 4 
Scope of investigations : 6 
Hatching in relation to wind dispersion 7 
Longevity of entrapped first-stage larvae 8 
Screen experiments 8 
Dispersion experiments, New Hampshire 
hills 14 
Page. 
Altitude experiment 15 
Observations on wind dispersion 17 
Observations for reinfestation 17 
Small larvae blown into ocean 18 
Feeding prior to dispersion 19 
Comparison of weather data .' 19 
Spread of gipsy moth 20 
Summary 21 
Bibliography 22 
INTRODUCTION. 
The territory infested by the gipsy moth (Porthetria dispar L.) is 
gradually increasing in area, and since isolated colonies are being 
found each year in woodlands and orchards remote from lines of 
gravel, the question as to their origin has become more urgent. 
Many agencies assist in the transportation of the moth in its various 
stages, but as previous experiments proved that small caterpillars are 
borne by the wind, it seemed desirable to ascertain to what extent 
this occurs and the maximum distance they may be blown under 
field conditions. Much depends upon this factor in diffusion, when 
devising methods of preventing the spread of this pest, and as a 
practical result of previous experiments tanglefoot has been used 
* extensively in colonies located in the outside infested towns. Trees 
are banded with tanglefoot to prevent the small larvae from ascending 
to the tops, and thus the chances that these larvae will be blown 
long distances are decreased. 
1 An extended report on one of the important phases of gipsy moth control work, conducted under the 
direction of the Bureau of Entomology, L. O. Howard, Chief, and in cooperation with the various 
States affected. 
96810°— Bull. 273—15 1 
