UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 273 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



SU^^mTU 



Washington, D. C. 



PROFESSIONAL PAPER 



SV& m T*SU 



August 24, 1915. 



DISPERSION OF GIPSY-MOTH LARV^ 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 eutrapped first-stage larvae 8 



Screen experiments 8 



Dispersion experiments, New Hampshire 



mils 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 



B ibliography „ 22 



INTRODUCTION. 



The territory infested by the gipsy moth (Porihetria 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 bunded with tanglefoot to prevent the small larvae from ascending 

 to the tops, and thus the chances that these larva) will be blown 

 long distances are decreased. 



' An extended report on one of the important phast lof glp . moth control work, conducted under the 

 direction of the Bureau of Entomology, L, 0. Howard, chief, and In cooperation with tho various 

 State ■ affected. 



96810"— Hull. 273— U 1 



