50 MASS. EXPERIMENT STATION BULLETIN 150. 



On August 15, 1912, 42 pupa of the spanworm, spoken of in last year's 

 report as having done serious damage on the Old Colony bog at Yar- 

 mouth, were collected. They were kept on moist sand in cans through 

 the fall, A\'inter and spring. Between June 6 and 15, 33 moths emerged 

 from these pupse, but no parasites were obtained from them. Three of the 

 pupae which failed to produce moths appeared to be in good condition 

 and were probably Icilled by overheating a few days before the moths 

 would have emerged. Of the 33 which emerged, 17 were females and 16 

 were males. These moths were protandrous in emerging, for before 

 June 11, 13 males and only 8 females emerged, while after June 10, 9 

 females and only 3 males emerged. 



The Old Colony bog was visited on June 13, and the moths of this insect 

 were found to be present in great numbers on an area of about 2 acres 

 (estimated) which had not been treated in any way to get rid of the insect 

 because that portion of the bog belonged to a separate and apparently 

 careless owner. It was estimated that three-fourths of the moths present 

 were males, though the proportions of the sexes were not carefuUj' ascer- 

 tained. Portions of the bog, which had been heavily infested in Jul}'- 

 and August, 1912, had been burned over in the latter half of August, and 

 other infested portions had been resanded with seven-eighths to one and 

 one-half inches of sand. Practically no moths of the spanworm were 

 found on June 13 on any of these treated portions, except where the 

 treated areas immediately adjoined untreated hea\aly infested areas. 

 Evidently the burning had effectively destroyed the pupae and the sanding 

 had smothered them. 



It should be noted that, though the bog had been completely under 

 water for over four months, the winter flowage had not drowned any con- 

 siderable percentage of the pupse. This seems remarkable, for they were 

 entirely naked {i.e., were without anj' cocoon), and they lay fully exposed 

 on the surface of the sand. Practically all of these pupae found on the 

 bog on June 13 showed distinct signs of life when they were picked up. 



At the time of the visit to this bog (June 13) the millers on the infested 

 portion were being caught and eaten (the males mostly, as this sex flew 

 up into the air readily, sometimes as high as 25 or 30 feet, while the females, 

 as a rule, being heavy with eggs and unable to fly well, stumbled and 

 flopped along the ground when attempting to do so) by swallows (two 

 barn swallows and a dozen or more tree swallows). These swallows were 

 flying back and forth like bats, and the clicking of their bills was incessant 

 as they captured the moths. 



On June 15 the eggs were dissected out of several plump female moths 

 and counted . These eggs were all bright green in color when fresh from the 

 moth, but they afterward turned yellowish. They numbered 295 in the 

 most productive moth and 187 in the least productive one. Eggs of this 

 insect were found hatching in the laboratory on June 19 and 20. 



On July 8 the Old Colony bog was visited again, and the following notes 



