248 MAINE AGRICULTURAL EXPERIMENT STATION. I907. 



weeds, the practice of fall plowing commends itself in this con- 

 nection and also the burning over of grassy and weedy spaces 

 in the vicinity of potato fields. As it seems not impossible, 

 although it has not been observed, that belated specimens might 

 under certain conditions remain upon potato vines slightly 

 infested and the oviparous females develop there, the custom 

 common through Aroostook County of burning the old potato 

 stalks to get them out of the way is commendable as a pre- 

 caution. 



5. If N. solanifolii continues to be a serious pest upon the 

 potato it may be advisable to drop the peas from the rotation. 



6. While under favorable conditions N. solanifolii is a seri- 

 ous pest upon the potato, there seems to be nothing better to 

 advise by way of direct remedy than to leave it to its natural 

 enemies, which sometimes, as the fungus of this present season, 

 serve practically to exterminate it over wide areas. 



7. The countless beak wounds inflicted upon the stalk and 

 leaves must render the potato more susceptible to fungus and 

 bacterial disease. Its presence, therefore, should emphasize 

 the need of careful Bordeaux sprays. 



Natural Enemies. 



1. Weather conditions stand high among the controlling 

 influences of aphid growth, heavy or continuous rains serving 

 as a check. 



2. Predaceous insects. Among these found feeding upon 

 A r . solanifolii in Maine may be mentioned 2 lady beetles, Adalia 

 bipunctata and Hippodamia i^-punctata, and larvae of syrphus 

 flies. 



3. Parasitic insects. Braconid parasites of the subfamily 

 Aphidiinae have been bred from N. solanifolii taken in this 

 State. 



4. Fungus parasites. Frequent mention has already been 

 made in this bulletin of the work of fungus upon N. solanifolii 

 at Houlton and also at Orono whence it was introduced into 

 the insectary. Dead specimens from both localities were sub- 

 mitted to Doctor Roland Thaxter, who kindly identified the 

 Orono species as E. planchoniana Cornu, and that from Houl- 

 ton as the more common E. aphidis. 



