The Aphididae of Nebraska 1 1 



the costal and discoidals subequal and together rather more than half the 

 posterior border. (An examination of fourteen specimens only showed 

 one with third discoidal forked in both wings and another with the same 

 vein forked on the left wing and second discoidal also forked near the 

 tip.) When newly hatched in the first stage the basal joint of the tarsus 

 is hardly perceptible and the tarsal hairs are simple. The antennae are 

 4-jointed, the basal joint half as long as the second, third and fourth, 

 somewhat longer and subequal ; fourth suddenly narrowed at tip ; the 

 promiscus reaches beyond the hind coxae. After the first molt the an- 

 tennae are 5-jointed, IV very short and almost globular; the promiscus 

 now reaches to middle coxae only. In the pupa stage the antennae are 

 6-jointed. 



Young from winged female similar to the same stage of its parent, 

 except in the promiscus reaching beyond anus. Length 0.15 mm. 



Galls on the narrow-leaved cottonwood (Populas angnstifo- 

 lia). A series of more or less confluent moniliform swellings on 

 the upper side of the leaf, each containing a single female, des- 

 tined to become winged, when it escapes from beneath, the 

 winged insect occupying the entire cavity of the gall. The galls 

 are often so plentiful as to cover nearly every leaf of the tree, 

 but other kinds, as P. monilifcra, P. tremuloides, etc., are not in- 

 jured, being entirely free from the galls of this louse. The galls 

 when not very numerous appear most commonly on the terminal 

 leaves of a twig. They form a confluent series of pale yellow 

 ovoid swellings, on each side of the midrib, recalling in the dis- 

 tance a lot of unripe cherries, or, again, the galls produced on a 

 true willow by the sawfly larva, Nematus salicis-pomam Walsh. 

 There are sometimes three rows of these swellings, and they are 

 not infrequently tinted red. There are, however, more often but 

 two rows, occupying nearly the whole space each side of the 

 midrib. The galls are formed by the folding under of the sides 

 of the leaf and bulging of the same around the insect, which is 

 always found solitary (Riley). 



On narrow-leaved cottonwood (Popitlus augiistifolia). Squaw 

 Canyon, Sioux Co., June 24, 1890. Only the youngest leaves 

 were affected, and only young, wingless lice were found. Pro- 

 fessor Bruner found it quite plentiful in Idaho and Utah in the 

 month of August; Colorado, July (Riley) ; Kansas (Monell). 



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