12 



BULLETIN 554, U. S. DEPARTMENT OF AGRICULTURE. 



on the average, 21 days. (See Table V.) Under natural bog con- 

 ditions, following the drawing of the winter flowage about May 10, 

 it is very likely that the pupal period is several days shorter in 

 duration than as stated. The pupa is always found with the head 

 pointing toward the neck of the cocoon, eventually permitting the 

 easy emergence of the moth. 



Table V. — Length of pupa stage of the cranberry girdler, Pemberton, N. J., 



191',. 



Experiment No. p g££ 



Date 



adult 



emerged. 



Length of 

 stage. 



Experiment No. 



Date of -|£te 

 pupation, j e ^u g lt d 



Length of 

 stage. 



1 



Apr. 28i 

 Apr. 29i 

 ...do 



( 2 ) 

 May 11 

 May 15 

 May 18 

 May 20 

 May 27 

 May 29 

 ...do 



Days. 



9 



Apr. 30 

 May 2 

 ...do 



( 2 ) 

 ( 2 ) 

 May 18 

 ...do.... 

 June 5 

 June 13 

 June 17 

 ...do.... 



Days. 



2 



12 

 16 

 19 

 21 

 28 

 30 

 29 



10 





3 



11 



16 



4 !...do 



5 ...do 



12 



13 



...do 



May 7 

 May 23 

 Mav 29 



...do 



16 

 29 



6 ...do 



14 



21 



7 ...do 



15 



19 



8 



Apr. 30 



16 



19 



Average days, 21.15. 



1 Approximate. 

 NATURAL ENEMIES. 



2 Died. 



Among the parasites there appear to be very few which attack the 

 cranberry girdler. No parasites were obtained in the rearing cages, 

 but occasionally when opening cocoons the remnants of a parasite 

 in one stage or another were found. From such findings two species 

 of Ichneumonida? were secured. The habit of concealed feeding of 

 the girdler larva? must be a great protection against parasitic ene , 

 and the winter flowing of the bogs probably also tends to lessen the 

 activities of parasites. 



In areas of severe girdler infestation spiders have been found to 

 be very abundant as well as have various species of ground bee s. 

 Among the ground beetles Harpalus caliginosus Fab. and Anisodoc- 

 tylus harrisii Lee. have been collected. 



Very often an area of vines infested with girdler larva? will be 

 invaded by field mice, and the burrows just beneath the surface will 

 run throughout the entire section. While mice occasionally cut off 

 cranberry vines which are in the line of a runway, they should be 

 classed as minor pests of the cranberry industry. The work of mice 

 may be recognized by the diagonal cut of the severed vine and the 

 furrows made across the end by their teeth. It is thought, however, 

 that the mice search for girdler larva? and are instrumental in reduc- 

 ing large infestations. They nest in roundish houses built of grasses 

 above the level of winter flowage. 



Among the birds which prey on insects the swallows are perhaps 

 the most useful in capturing girdler moths. At Howardville, N. J., 

 a swallow followed the writer the length of one of the bogs, and as 



