396 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



Through the kindness of several southern entomologists, elm leaf 

 curl in considerable abundance with winged forms ready for migration 

 was secured in May. These migrants as previously explained (Science, 

 Vol. 36, pp. 30-31) were caged over apple seedlings greenhouse-grown 

 for the purpose, the seeds having been planted in December 1911 and 

 January 1912. A few very successful colonies of woolly aphids were 

 thus established on apple seedlings by the progeny of the elm migrants, 

 the earliest of which was one started by migrants received May 12 

 which is still flourishing, even in indoor conditions, at the time this 

 paper goes to press. 



Encouraged by the successful indoor tests/ outdoor tests under more 

 favorable conditions were made when the winged forms appeared in 

 this vicinity. 



Water shoots had been allowed to grow about the base of a mountain 

 ash, Pyrus sp. on the campus and up to June 21 this tree and the shoots 

 were free from woolly colonies. As the migrants are much more docile 

 about sundown than earlier in the day, I placed several hundred elm 

 migrants at the base of the water shooots, about 7 p. m. on June 21. 

 They moved about a little, most of them creeping to the ventral side 

 of a leaf and remaining there; and during the night producing nymphs 

 which sought the leaf axils of the water shoots so that by the after- 

 noon of June 22 the tiny nymphs had already fed enough and secreted 

 enough white wax to give the typical "woolly" appearance to the 

 colonies. These and their progeny thrived on the mountain ash in 

 a perfectly normal way for the woolly aphid of the apple. 



Similar successful results were obtained by evening ''plantings" 

 of elm migrants upon uninfested water shoots of apple on June 24. 



By this time the elm curl migrants were settling of their own accord 

 on leaves of both mountain ash and apple and by June 28 colonies of 



1 A very high percent of the indoor attempts to estabhsh colonies upon apple 

 seedlings, both with the material from the south and with Maine collections were 

 unsuccessful. The reasons for the failures I do not know. The seedlings were 

 grown from seeds removed from apples on the Maine market and it is possible that 

 many of these plants were varieties not susceptible to attack. Though healthy, the 

 seedhngs were rather a scrubby lot, having received no fertilizer on the theory that 

 "neglected orchards suffer worst from attacks of woolly aphids." The later out- 

 door experiments showed that the most vigorously growing water shoots of apple 

 and mountain ash (Pyrus) were most readily accepted, which would indicate that if 

 the seedlings had been forced as they are in the nursery they might have been better 

 bait. I think, too, that freshly moulted migrants are often too restl&ss and instinc- 

 tively impelled to flight and dispersal to take kindly to confinement. Whatever the 

 trouble, I have often had cause to recall Riley's remark on this species, — "There is 

 much greater difficulty in fully tracing the life-history of one of these small creatuies 

 than might be supposed. They languish in confinement and ill bear handling." 



