Insects troubling cherries are numerous but hardly as destructive as with other tree-fruits. Entomologists list about 40 species of insects attacking cherries and about as many more occasionally attack the varieties of one or the other of the two cultivated species. The majority of these pests came with the tree from its habitat over the sea but several have come from the wild cherries of this continent.
Of the pests peculiar to the cherry alone, possibly the cherry fruit maggot1 (Rhagoletis cingulata Loew) is, the country over, as troublesome as any. The adult insect is a small fly with barred wings which lays eggs under the skin of the cherry in mid-summer. From these eggs small, whitish maggots about one-third of an inch long hatch and eat out a cavity in the ripening fruit. These maggots when full grown pupate in the ground and remain there until the following season. The only effective preventive or remedial measure to take against the pest in large orchards is to spray with a sweetened arsenical, but in small plantations chickens are fairly effective in scratching up and eating the pupating maggots.
The cherry fruit maggot is probably responsible for most of the wormy cherries in New York but the plum curculio is also a cause of wormy fruits and in some seasons is a most formidable pest. This curculio2 (Conotrachelus nenuphar Herbst) is a rough, grayish snout-beetle somewhat less than a quarter of an inch in length, so familiar an insect as scarcely to need further description. The female beetle pierces the skin of the young cherries and places an egg in the puncture. About this cavity she gouges out a crescent-shaped trench, this cut or sting being a most discouraging sign to the cherry-grower, for he well knows that from the eggs come, within a week or two, white and footless grubs which burrow to the stone and make "wormy fruit."Some of the infested cherries drop but many remain eventually to distract the housewife and those who eat cherries out of hand. jarring the beetles from the trees, a method employed by plum-growers, is quite too expensive and ineffective for the cherry-grower and poisoning with an arsenate is the only practical means of combating the pest. Rubbish and vegetation offer hiding places for the insects and, therefore, cultivated orchards are freer from curculio than those laid down to grass. There are no curculio-proof cherries but, as with plums, the thin-skinned varieties are damaged most by the insect.
The grub of the plum curculio is easily distinguished from the cherry fruit maggot. This "worm "is the larva of a beetle, a true grub, footless and with a brownish, horny head while the cherry fruit maggot, the larva of a two-winged insect, is a true maggot like that which comes from the common housefly and hardly to be distinguished from the apple maggot. It is important to be able to distinguish in wormy cherries the grub of the curculio from the cherry fruit maggot in order to know and understand the nature of the two enemies in combating them.
The dreaded San Jose scale3 (Aspidiotus perniciosus Comstock) is rather less harmful to cherries than to other tree-fruits and yet is sometimes a serious pest on Sweet Cherries. Sour Cherries are almost immune. The insect is now so well known in all fruit-growing regions that it needs no description. It is usually first recognized by its work, evidence of its presence being dead or dying twigs oftentimes the whole tree is moribund. Examination shows the twigs or trees to be covered with myriads of minute scales, the size of a small pinhead, which give the infested bark a scurfy, ashy look. If the bark be cut or scraped a reddish discoloration is found. Leaves and fruit as well as bark are infested, the insidious pest, however, usually first gaining a foothold on the trunks or a large branch. Cherry-growers, in common with all fruit-growers, find the lime and sulphur solution the most effective spray in combating this insect.
Several other scale insects feed on the cherries and, now and then, become pestiferous; among these the following may be named: The European fruit lecanium4 (Lecanium corni Bouche) occasionally does a great deal of damage in New York and now and then destroys the whole crop in an orchard. The winter treatment for San Jose scale is used to control this pest, but usually such treatment is supplemented by a summer spray about July first with such contact sprays as whale oil soap and kerosene emulsion. The fruit pulvinaria (Pulvinaria amygdali Cockerell), the mealy bug (Pseudococcus longispinus Targioni), the scurfy scale (Chionaspis furfura Pitch), the West Indian peach scale (Aulacaspis pentagona Targioni), the Putnam scale (Aspidiotus ancylus Putnaxn), the walnut scale (Aspidiotus juglans-regiae Comstock), Howard's scale (Aspidiolus howardii Cockerell), the European fruit scale (Aspidiotus ostreaeformis Curtis), the red scale of California (Chrysomphalus aurantii Maskell), the oyster-shell scale (Lepidosaphes ulmi Linnaeus), and the soft scale (Coccus hesperidum Linnaeus), are all more or less cornmon.
1 Slingerland, M.V. Bul. Cor. Ag. Ex. Sta. 272: 1899.
2 Riley,C.V. An. Rpt. State Entmo. Mo. 1:50-56. 1869:3:11-29. 1871.
3 Marlatt, C.L. The San Jose or Chinese Scale, U.S.D.A. Bw. Ent. Bul. 62:1-89. 1906.
4 Lowe, V.H. The New York Plum Lecanium, N. Y. Sta. Bul. 136:583-1897.
5 Beutenmueller, W. Sesiidae of America, etc. 266-271. 1901.
6 ibid. 291-292. 1901,
7 Riley,C.V. An. Rpt. State Entomo. Mo. 1:46-47-1869-
8 Lowe,V.H. N.Y. Sta. Bul. 180:122-128. 1900.
9 Wilson,W.F. The Peach-tree Bark-beetle, U.S.D.A. Bur. Ent. Bul. 68:91-108. 1909.
10 Lowe, V.H. The Apple-tree Tent Caterpillar, N. Y. Sta. Bul. 152:279-293. 1898.
11 Riley,C.V. An. Rpt. State Entom. Mo. 2:94-103. 1870.
12 Ibid. 7:83-90. 1875.