A HISTORY OF CORNWALL 



very common locally on coltsfoot. S. sisymbrii is plentiful on hedge-mustard near Falmouth and at 

 Marazion and on turnips at Kea. S. olivata has been taken in abundance on Carduus lanceolatus 

 near Saltash and on C. acaulis in the west of the county. 



Phorodon humuli, var. mahaleb, is not uncommon about Truro on the sloe, and has been found 

 on the Czar plum. P. galeopsidis has been much in evidence lately in the middle of the county, 

 especially on woundwort. It also occurs at Liskeard on Lamium intermedium, and in 1904 was 

 disagreeably abundant at Truro on Chinese artichokes. Myzus cerasi occurs about Truro on black 

 currant ; at Bodmin last year it was unpleasantly common on cherry trees. M. persicae is widely 

 distributed on peach and occasionally on apple trees. M. ribis is usually abundant, and causes the 

 large reddish or brownish blotches on the leaves of the red currant. It is often common on 

 gooseberry leaves. Depranmipbon platanoides is plentiful on sycamore and maple. 



Rhopalosiphon ribis is abundant everywhere on the leaves of black currants, causing the forma- 

 tion of bright orange, reddish, and brown elevations, and making the leaves curl irregularly and so 

 give shelter to hundreds of aphides. Occasionally it completely ruins the black-currant crop. At 

 Bodmin it was fairly common in 1904 on ornamental currant. R. lactucae is not uncommon on 

 sow-thistle and nipplewort, and in 1902 appeared at Mawgan-in-Pyder on Hieracium aurantiacum. 

 R. nymphaeae occurs on water plantain at Newquay. R. berberidis has been taken at Truro some- 

 what sparingly on Berberis vulgaris, B. darwinii, and Mahonia aquifolia. R. dianthi did damage m 



1904 to some of the early potatoes at Penzance ; it has also been sent in several times on turnips 

 and swedes, and last year attacked the foliage of the late tulips and of Mrs. Sinkins pink in the 

 botanical garden at the Technical Schools, Truro. Melanoxanthus salicii has been repeatedly 

 obtained from willows by the side of the Lynher. Siphocoryne pastinacae proved troublesome in 



1905 on celery at Penzance, and in 1901 attacked parsley about Truro with disastrous results. 

 S. xyhstei is locally very common on honeysuckle in the St. Agnes HistriW. 5. fieniculi has been 

 taken on garden fennel at Saltash and at Falmouth, and at Penryn quickly destroyed the fbltage of 

 a promising bed of carrots. S. capreae is widely spread on willows in the east of the county. 



Aphis brassicae occasionally attacks cabbages and various cruciferous weeds in considerable 

 numbers. In 1899 it caused great damage to the broccoli plants about St. Burian. The top 

 leaves of the growing shoots of the whitethorn are frequently blistered and curled up into a tangled 

 mass by the action of A. crataegi. A. malvae is a common greenhouse pest, which occasionally 

 attacks various herbaceous plants in the open. A. mali sometimes causes great damage to the 

 orchards of the county by destroying the foliage ; in 1901 and 1902 it was very troublesome at 

 Penzance, and in 1904 appeared in great numbers near Launceston and Callington. A. urticaria is 

 frequently seen on the bramble and the gooseberry as well as on nettles. In 1903 it proved 

 troublesome in Truro on ornamental gourds. A. pennicillata has been noticed every year on willow 

 herbs. Single cactus dahlias at Truro were in several cases last year attacked by A. pyraria. 

 A. scabiosae is generally distributed, but not usually common ; it is a most varied feeder. A. sorbi is 

 widespread but local, and occurs chiefly on mountain ash. A. tanacetina in 1904 appeared in 

 numbers on a bed of Swan River daisy at Truro. A. pruni is in some years most destructive to 

 the foliage of the apple, and in 1902 some of the trees in an orchard near Callington had almost 

 every leaf rolled up regularly, lined inside with the characteristic sticky and mealy exudation, and 

 literally filled with both winged and wingless forms of this species. Several of the plums were also 

 severely attacked ; at St. Columb a wall-peach was noticed in a similar condition, and at Truro 

 Pyrus japonica was rendered unsightly. A. hieracii is widely spread on the leaves of hogweed. 

 A. petasitidis occurs on the winter heliotrope, Petasites fragrans at Penwerris, Falmouth ; and 

 A. lycbnidis locally on ivy. A. hederae is common on ivy and is occasionally found on holly. The 

 leaves and flowers of the guelder rose are at times attacked by A. viburni. A. jacobea is often 

 abundant on ragwort, groundsel, and Senecio aquatica ; and A. rumids, the 'collier' and 'black 

 dolphin ' of the gardener, is often conspicuous on broad beans, in some seasons has badly affected 

 the turnip crop, and in 1901 it destroyed a field of mangels near Wadebridge ; neglected docks 

 and thistles often swarm with it. A. laburni, A. papaveris, A. cardui, A. instabilis, and A. sambuci 

 all enter an appearance from time to time. A. opima is often common on neglected cinerarias, and 

 A. myoiotidis has been identified from several different plants. A. amygdali, in Cornwall as else- 

 where, is the chief insect pest on peaches and nectarines, causing the leaves to curl and drop, and in 

 bad cases completely stripping the branches. Occasionally these trees are attacked by Hyalopterus 

 pruni, which produces characteristic white hoary masses under the leaves and gums them over with 

 a glutinous secretion. 



The singular dimorphic Chaitophorus aceris is not uncommon on sycamores and maples. 

 C. salicivorus is apparently widespread, but local. C, populi is in some years unfortunately prevalent 

 in the plum gardens, Truro. The birch-frequenting Callipterus betularius and C. betulicola have both 

 been procured near Launceston, but are evidently scarce. C. coryli is generally distributed, but 

 varies very greatly in numbers. C. quercus is local, but often abundant ; at St. Germans it occurs 

 on ilex. 



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