THE GIPSY MOTH ON CEANBEERY BOGS. 7 



As a result of these observations it will be seen that the time of 

 greatest dispersion follows from 13 to 14 days after hatching. It 

 should be noted, however, that on uplands independent observations 

 have shown that this period is shorter. 



With the exception of the year 1917, the woodland surrounding 

 Muddy Pond Bog was lightly infested with the gipsy moth. Dur- 

 ing that year there were a few scattered pockets on the western edge 

 of the bog where a medium infestation existed. No heavy infesta- 

 tions were noted during the years that these experiments were con- 

 ducted. The results of the observations for 1917 may therefore be 

 taken as illustrating what might reasonably be expected in any sim- 

 ilar infestation, and are given in detail iii Table 2. 



Table 2. — Trap record for the season of 1911 giving the total number of 'gipsy 

 moth lorvce taken from each trap and total for each day of dispersion, Muddy 

 Pond Bog, Carver, Mass. 



Trap No. 



May. 













June. 













Total. 



26 



31 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



14 



1.. 





 4 

 3 



16 

 11 



5 



4 



(') 



(')■ 



(1) 



11 



15 



4 



3 

 12 

 10 

 (1) 

 26 

 17 

 9 



4 

 12 

 11 

 22 

 28 

 12 



3 



24 



(1) 



(1) 



(1) 



169 

 86 

 58 



8 

 43 

 38 

 11 

 135 

 149 

 47 



8 



0) 



8 



(1) 



46 



54 



20 



3 

 35 



8 

 10 

 10 

 11 



3 







(') 

 (1) 



10 



4 

 2 





 3 

 2 

 1 

 4 

 5 

 1 





 



(') 



(') 

 2 

 2 

 2 





 4 



7 

 7 

 3 







(') 



(1) 



(0 



1 







2 



54 



2 



113 



3 



80 



4 



44 



7 



465 



8 



373 



9 



159 







Total... 



39 



34 



77 



92 



337 



431 



133 



80 



16 



16 



6 



21 



3 



1,288 



1 No examinations made. 



From Table 2 it will be noted that the largest numbers of larvae 

 were taken from the traps nearest the border of the bog, the number 

 gradually diminishing as the distance from the border increased. 



It is interesting to note the results secured on the two vertical 

 traps. On No. 10, which was constructed of wall board, 255 lan^se 

 were caught, while on No. 11, which was a wire trap, only 121 were 

 secured. As these two traps were placed in equally favorable loca- 

 tions, it is evident that many larvae passed through the wire screen. 

 It is probable that wire treated with commercial sticky tree-banding 

 material but having one-fourth-inch mesh would be much more effec- 

 tive. It is also interesting to note the difference between the number 

 of larvae taken on horizontal trap No. 9 and vertical trap No. 10. 

 They had the same number of square feet of surface exposed, and 

 although they were located near together, 159 were taken on the 

 former and 255 on the latter. This shows conclusively that the num- 

 ber of wind-borne larvae caught on a vertical surface is not a fair 

 index of the number that will drop on a horizontal area of the same 

 size. The density of infestation on low vegetation, when insects are 



