Jan., 1921] Life History of Corythiicha Celtidis 105 



two clusters on a single leaf. In many cases each cluster was 

 found in the basal half of the leaf and the first nymphal feeding 

 took place in this area. 



Egg. Length, 0.55 mm. Greatest width, 0.17 mm. Sul^elliptical, 

 one side more convex than the other; tapering most at basal end which 

 is acute with rounded end, end slightly constricted where it is inserted 

 in the leaf tissue; sides of apical half tapering slightly; extremity of 

 apical end truncate with rim-like collar and projecting cone-shaped cap. 

 Cap white, remainder of egg brownish to brownish black, shining. 



First Stage Nymph. Length exclusive of spines, 0.61 mm. Greatest 

 width exclusive of spines, 0.19 mm. Subelliptical. whitish or slightly 

 brownish with a median dorsal, white area which includes part of the 

 metathorax and the first two abdominal segments. Armature apparently 

 similar to that of second stage nymph except that the only apparent 

 tubercles are those on the head and the tubercular bases of the median 

 abdominal spines. Remainder of armature appears to consist of simple 

 spines with slightly tuberculate bases. Ventral surface, legs, antennae 

 whitish, most of spines white. Abdomen margined. 



Second Stage Nymph. Length exclusive of spines, 0.78 mm. Great- 

 est Avidth exclusive of spines, 0.31 mm. Oval elongate; similar in color 

 and armature to the third stage nymph. Armatrue more pronounced 

 than in first stage. 



Third vStage Nymph. Length exclusive of spines, 1.10 mm. Great- 

 est width exclusive of spines, 0.40 mm. Oval; armature similar to that 

 of fourth stage nymph except that the smaller spines on the margins of 

 the thoracic lobes are absent and the lateral abdominal spines are single 

 instead of double. Color and markings similar to those of fourth stage 

 nymph. Color slightly darker than that of second stage nymph. 



Fourth Stage Nymph. Length exclusive of spines 1.18 mm. 

 Greatest width exclusive of spines 0.68 mm. More oval than third 

 stage nymph. Color and markings similar to those of fifth stage nymph. 

 Annature similar to that of fifth stage except that in addition, the second 

 and third abdominal segments bear single lateral spines. vSides of pro- 

 thorax produced laterally. Mesothoracic lobes reaching to second 

 abdominal segment. 



Fifth Stage Nymph. Length exclusive of spines, 1.75 mm. Greatest 

 width exclusive of spines, 0.78 mm. Oval, dorsal surface dark brown, 

 except for lateral half of prothoracic lobes and tubercles located on this 

 surface, median dorsal portion of mesothorax, metathorax, and first 

 abdominal segment and spines, posterior half of mesothoracic lobes and 

 tubercles on this surface, the median portion of the eighth abdominal 

 segment, the margins of abdominal segments seven and eight, the dorsal 

 and lateral abdominal spines which are light. Antennae, sparsely hairy, 

 four-jointed, third joint about twice as long as the first two 

 combined, fourth joint clubbed. Antennas white except for 

 clubs which are brownish. Eyes prominent consisting of numerous, 

 reddish ommatidia. Head bears a pair of separated spines 



