336 MAINE AGRICULTURAL EXPERIMENT STATION. I916. 



such a colony could maintain itself on the apple without fresh 

 material from the elm I do not know.* 



I am certain that in Maine the natural enemies of the woolly 

 aphid would cut its career short and that it would not assume 

 the status of a pest of consequence if it did not shift its food 

 plant. As it is, a two days quest in the vicinity of Orono early 

 in September, 1913, failed to locate a single colony which was 

 not well nigh demolished by chalcid parasites and the colonies 

 of 1912 met a similar fate the preceding year by virtue of 

 syrphus maggots. Lady bird beetles are also very active some 

 seasons. While in the elm leaf this aphid is preyed upon by 

 syrphus maggots, capsid bugs and lady birds. 



As if the hibernating nymphs were not enough to bewilder 

 one, the case of the woolly aphid of the apple is still further 

 complicated by the root colonies which although hidden in their 

 operations are really often much more pernicious than the colo- 

 nies on trunk and branches. These root colonies ordinarily 

 remain underground all the year round, apparently until the 

 roots become too badly demolished for feeding purposes. 



Economic Status. 



The danger from the woolly aphid is greatest to nursery 

 stock and young orchards. Mr. Marlatt (Journal of Economic 

 Entomology, Vol. 4, pp. 116-117) in recording the use of 

 American-grown apple seedlings says : — "Mr. F. W. Watson, 

 of Topeka, Kans., in an article in the National Nurseryman for 

 January, 1910, p. 437, on 'American-grown Apple Seedlings,' 

 states that from twenty to forty million of American-grown 

 apple seedlings are used in this country every year, the pro 

 duction of about a dozen nursery firms. The bulk of the seed 

 used comes from France, and therefore is of the same stock as 

 the imported French seedlings." 



Mr. Lohrenz (1911) in recording observations on two-year- 

 old nursery stock made at three nurseries containing respectively 



*We have an exact parallel in Pemphigus tessellata or the woolly 

 aphid of the alder with a cycle including a spring migration from the 

 maple leaf to alder and a fall or return migration to the maple and also 

 a generation of hibernating nymphs remaining under leaves about the 

 base of the alder during the winter and ascending to the stem before 

 feeding in the spring. 



