1056 WALTER H. WELLHOUSE 



Tingitidae 



bellula Gibson, Corythucha (Plates LXXII and LXXIII) 



Although the original description of Corythucha bellula was published 

 but recently (Gibson, 1918), the species seems to be fairly common where 

 its host plants occur, and it has probably been confused with C. cydoniae 

 by earlier observers who must have seen it on the hawthorns. It has 

 been found by Drake in Ohio and by Griddle in Manitoba. 



The host plants include those species of Crataegus that have hairy leaf 

 veins, and alsoAlnus incana and Ribes oxyacanthoides. The writer has found 

 the insect breeding in abundance on Crataegus neofluvialis and to some 

 extent on C. albicans and C. punctata. The hawthorns with smooth leaves, 

 such as C. pruinosa, C. crus-galli, and C. oxyacantha, even when their 

 branches were intermingled with thos? of trees that were badly infested, 

 revealed no nymphs nor eggs. 



In a large thicket of C. neofluvialis trees near the Cornell University 

 campus, the leaves were so discolored by the end of July that they attracted 

 attention several hundred yards away. By the middle of August the 

 leaves were falling, and the branches were bare by September 1. No 

 fruit matured on these trees. A few scattered trees of this species in other 

 directions from the city were also badly infested. Individual trees of 

 C. albicans and C. punctata showed an occasional branch badly infested 

 and with leaves discolored. The injury is caused by the nymphs and 

 the adults puncturing the under surface of the leaf and sucking the sap, 

 producing at first a mottled effect due to the pale areas around the feeding 

 punctures, while later the leaf turns brown and falls to the ground. Orna- 

 mental plantings of Crataegus in parks and gardens are rendered unsightly 

 and weakened by this injury. 



There are two generations annually at Ithaca. The first brood hatches 

 in July from eggs laid in late May and in June, and the nymphs become 

 mature in from twenty to twenty-five days. The second-brood eggs are 

 laid in late July and in August, and the adults appear in late August and 

 in September. 



The adults of the second brood hibernate among the fallen leaves and 

 in crevices of the bark. Many of them remain on the leaves on which 

 they were feeding before the leaves fell. They appeared the last of 

 May, and during early June were feeding on the new Crataegus leaves. 

 As a rule only one pair of adults was found on a leaf, and they remained 

 feeding and ovipositing on that same leaf for several days. After emer- 

 gence from the nymphal skin in September, the adults of the second brood 

 continue feeding on the leaves until they fall, in late September or in 

 October, 



The egg is subelliptical, with the basal end rounded and the apical end 

 bent slightly to one side and capped with a rather broad cylindrical collar 



