J. C. F. Fryer 111 



one or other was present. Further they were absent from the un- 

 affected orchards with the exception of one in Worcester where 0. mar- 

 ginalis was recorded as present from two specimens only. It therefore 

 appears that one or both of these species are responsible for the injury, 

 and this opinion is strengthened by an experiment carried out by the 

 proprietor of an affected orchard in Worcester. This experiment 

 consisted in excluding the larvae of these species from a number of 

 trusses and also in enclosing them with others. The trusses from which 

 the bugs were excluded developed sound fruit, while the apples enclosed 

 with them sustained typical capsid damage. It is hoped to repeat 

 this experiment with P. nigicollis and 0. marginalis separately, in order 

 to confirm suspicion as to their both being responsible for damage — 

 in the meantime they must be left to share the responsibility between 

 them. In colour 0. marginalis and P. rugicollis differ from Psallus and 

 Atractotomus in being green or yellowish-green ; they closely resemble 

 each other superficially and may easily be confused in the field. The 

 presence of a rounded ridge or collar towards the anterior margin of 

 the pronotum will always distinguish P. rugicollis from an Orthotylus, 

 while in addition the former species is broader and stouter than the 

 latter, characters which give it a somewhat different appearance. Both 

 species are on Theobald's list of suspects, in his articles on the subject, in 

 the Joiirnal of Wye College, which also contains a quotation from Schoyen 

 to the effect that these species are harmful to apple and currant in 

 Sweden. Of neither species is the life history known. Mr E. A. Butler, 

 who was consulted on the subject, kindly gave the information that 

 both species were usually found on willow or alder, though Renter, who 

 described 0. marginalis, mentions apple as one of its food plants. Further, 

 in Mr Butler's experiences, these species appear rather late in the season, 

 larvae being found in June and July, and adults at the end of the latter 

 month and in August. In the cases now under consideration, P. rugi- 

 collis was adult in Suffolk on the 13th June and one or two pairings 

 were then observed. 0. marginalis was adult in Worcester on the 

 24th June, but many specimens were still immature, and it appears 

 to be a later insect than P. rugicollis. Both species, however, must 

 have hatched towards the end of April and there is thus a considerable 

 discrepancy between the observations here recorded and those of 

 Mr Butler. The possibility of two broods naturally suggested itself 

 but this is considered as most unlikely by authorities on the Hemiptera. 

 Examples sleeved on apple trees in June failed to produce a second 

 brood, and up to the present no eggs have been discovered, and their 

 exact situation is unknown. It is assumed temporarily that apple has 



