166 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



burdock and giant bur-elder, the last plant being, for the two seasons 

 during which this pest was under observation, the worst affected. 

 On August 1st two larvfe of P. nitela were found in giant ragweed, 

 with their entrance holes twenty-one inches above the ground, and 

 three other larvse on the same date were discovered with entrance 

 holes six feet above the ground. On the same date twelve nitela 

 larvffi were found in a single giant bur-elder three feet high. Some 

 of these were in the stalk, and some in the branches. In every case 

 the burrow ascended from the entrance hole. On September 3d 

 many empty burrows were found (evidently of both P. nitela and 

 P. cataphracta) in hemp and other plants, indicating that a large 

 per cent of the larvee enter the ground to pupate. 



P. CATAPHRACTA : On July l-tth these were first observed working 

 on young box elders. From this date on they were found to be quite 

 common until nearly August 23d, when the last found larvae pupated 

 in captivity. Pupation, however, began August 7th, which is about 

 the same date it was observed last year. On August 13th the first 

 moth in captivity emerged. 



The food plants as observed in 1909 are as follows : Burdock, box 

 elder, giant bur-elder, hollyhock, cosmos, peony, larkspur, dahlia, 

 thistle, aster, ragweed, tiger lily. It was not found at all in either 

 hemp or golden glow this year. In both 1908 and 1909 it was found 

 most common in burdock. The highest entrance hole in any plant 

 found this year was four feet and two inches from the ground. The 

 burrows did not extend below the lowest hole in any case. I wish to 

 state, however, that from personal observation I do not think it safe 

 to say that they never burrow below the entrance hole, since I believe 

 I have sometimes found the galleries in this position. 



Observations on the Migrations of the Larvae in Search of Food 

 Plants: As shown above, the larva^ of one of these species, and 

 probably both, may infest two food plants, and experiments were 

 carried on with a number of nearly or quite full grown larvas to 

 observe their movements in seeking food. Larva were placed in 

 various locations in our experiment garden, and their movements 

 watched for several hours, frequently until they stopped apparently 

 exhausted and finally died without being allowed to enter any food 

 plant. It would seem from these observations, in which we marked 

 carefully the course of each larva, that they seldom if ever travel 

 any considerable distance in a straight line from the place where they 

 first hatch. The caterpillar making the best record in actual distance, 

 traveled in all seventy-nine feet before stopping from exhaustion, 

 but this course was so irregular and tortuous that when it finished 



