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The Strawberry Aleyrodes, Aleyrodes packardi 



Morrill. 



This well known and widely spread insect was for many years 

 believed to be identical with the common greenhouse Aleyrodes. 

 Packard, who first mentioned this insect in the American Naturalist 

 (i) as occurring in large numbers on strawberry plants at Amherst, 

 Mass., referred it to the species " vaporarium " (vaporariorum). This 

 was a very excusable error, as we are justified in separating the two 

 species only after a critical study of all the stages of each, laying 

 special stress upon the range of variation in their structure. Since 

 this first mention the insect* has been reported several times as oc- 

 curring on strawberries (in such regions) in Ohio (7), Kentucky, (4, 

 5, 8, 10, 12), Southeastern New York (9) and Connecticut (10, 12). 



The food plants of the species, as far as known, are very lim- 

 ited. Besides the strawberry, pupae of this insect have been found 

 in small numbers on ash, spiraea and camperdown elms. 



I have recently described (11) all the stages of the strawberry 

 Aleyrodes, and have briefly tabulated the differences between it and 

 the greenhouse Aleyrodes. I will here consider more in detail the 

 points wherein the former species differs from the latter. 



Egg. Length varies from .23 to .24 mm. ; greatest width from 

 .08 to .094 mm. 



First Instar (Plate VI, Fig. 33). Only sixteen pairs of mar- 

 ginal spines are present in this instar, there being none to correspond 

 in position to the seventh and ninth pairs of A. vaporariorum. The 

 average comparative lengths of these spines in A. packardi are about 

 as follows : 



* I have positively identified specimens from Kentucky believed to be A. vaporariorum 

 as belonging to A. packardi. Ouaintance (9) has considered specimens from New York 

 state on strawberries which were too poor for positive identification as "much like A. 

 vaporariorum.' 1 '' My experience with strawberry plants growing in a plant house thickly 

 infested with A. vaporariorum goes to show that while the larva of this species will grow 

 to maturity on that plant if transferred in the first instar, the adults show no liking for it, 

 and are almost never observed even resting on its leaves. On such a plant I once found a 

 very few pupa cases, which were, however, too poor for identification. It is possible that 

 they were A. vaporariorum. I have never found an A. vaporariorum on a strawberry 

 plant out of doors. On the whole, therefore, I feel justified in considering all Aleyrodes 

 which have been reported as occurring on strawberries in this country and taken for 

 A. vaporariorum as belonging to the species packardi. 



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