Feb. is, 1918 Gipsy-Moth Larva and Blister-Rust 461 



To determine the approximate amount of spore material passed through 

 the alimentary tract, 20 larvae were placed on fresh cankers in a feeding 

 tray. After they were settled and had fed normally for several hours, a 

 sheet of paper was placed under the cankers for the collection of pellets. 

 A total of 423 pellets were dropped within a period of 13 hours. Counts 

 of the spores in these pellets gave from 3,960 to 12,450, with an average 

 of 8, 1 60, which is at the rate of 318,616 spores excreted per day per larva. 



Germination tests made of the spores on the bodies of larvae collected 

 on cankers gave positive results, and approximately the same percentage 

 of germination was observed as on spores taken directly from these 

 cankers. Germination tests of spores in pellets have given very poor 

 results; in only one case did several spores germinate. In many cases 

 spores taken directly from these cankers also failed to germinate in 

 laboratory tests. 



WIND DISPERSION OF LARVAE AS A FACTOR IN BLISTER-RUST SPREAD 



At Kittery Point, Me., aeciospores were produced from April 29 to 

 July i, with maximum spore production from May 10 to 25. Collins * 

 gives the hatching period for gipsy moth larvae in this section for 1912, 

 1913, and 1914 as May i to 23, April 29 to May 14, and May n to 28, 

 respectively. The season of 1917 was approximately one week later than 

 usual. The period of wind dispersion of larvae is given as ranging from 

 1 8 to 30 days, starting one to two weeks after the first caterpillars Latched. 

 Observations by the writers showed varying numbers of larvae feeding on 

 blisters from May 25 to June 25. 



Collins 2 working with wind dispersion of larvae of the gipsy moth over 

 a series of several years showed that they were carried in wind currents 

 to distances as great as 20 miles. The same author states that approxi- 

 mately 50 per cent of the larvae caught at distances of 6 miles or less had 

 fed previously. 



The writers, using fly-paper traps, placed 10 to 30 feet from the nearest 

 pine infection, and so arranged as to exclude larvae that may have reached 

 the trap by crawling, caught 75 small larvae. Four of these caterpillars 

 had, respectively, 35, 105, 185, and 2,180 aeciospores on their bodies, 

 which establishes the fact of local wind dispersion of aeciospore-bearing 

 gipsy-moth larvae. That spores carried on bodies of larvae may remain 

 viable for a considerable length of time is borne out in viability tests 

 under laboratory conditions, wherein aeciospores germinated after 

 remaining in vials for a period of two months. 



Examination of wild and cultivated species of Ribes at various points 

 throughout Kittery Township showed an abundance of gipsy-moth 

 larvae feeding on the foliage, and in many cases they were observed 

 crawling on the under surfaces of leaves. Quite a number of the larva- 



1 COLLINS, C. W. 1915. Op. cit. a COLLINS, C. W. 1917. Op. cit. 



