71 



Parrott (P. J.), Gloyer (W. 0.) & Fulton (B. B.). Some Studies 

 on the Snowy Tree-CriCket with Reference to an Apple Barli 

 Disease. — Jl. Econ. Entom., Concord, viii, no. 6. December 1915, 

 pp. 535-541. 



Oecanthus niveus (snowy tree-cricket) is connected with the spread 

 of a bark disease of apple, due to a fungus, Leptosphaeria coniothyrium, 

 Sacc. The wounds produced in the bark by the insect are discoloured 

 or dead, while the bark within the area of infection is slightly depressed 

 and may be separated from the sound bark by a crack. In more 

 advanced stages the cracks widen and afford shelter for woolly aphis 

 [Eriosoma lanigerum]. In April or May a gummy, reddish-coloured 

 fluid is exuded from the punctures. This fungus has previously been 

 recorded on apples and roses at Washington, D.C., and on raspberries 

 in New York. In raspberries, the fruiting canes are chiefly injured. 

 According to Clinton, infection occurs in wounds made by the removal 

 of branches, by the oviposition of 0. niveus, etc. The facts that the 

 blight is abundant on raspberries and that, while the tree-crickets 

 occur in great numbers on raspberries, they prefer apple wood for 

 oviposition, afford evidence that these insects are concerned in infecting 

 apple trees with the disease. Tree-crickets are omnivorous in habit. 

 In the early stages, the food consists of Aphids, leaf-hoppers, Tingitid 

 bugs and scale-insects ; when mature, they feed on the floral parts of 

 various plants, on leaves, fruit and fungi present in bark and decaying 

 vegetation. The majority of eggs of 0. niveus have been found in 

 apple, plum, cherry and elm. In the apple, deposition of eggs on the 

 smaller branches occurs near the thickened bark at the bases of the 

 twigs ; in the raspberry, the eggs are inserted at the sides of the buds 

 in the fleshy parts of the axils of the leaves. Infection of apple bark 

 might take place as the result (1) of wounds produced by the gnawing 

 of the bark by the female before oviposition ; (2) of the adhesive 

 substance discharged at oviposition, which serves to collect and retain 

 the spores ; (3) of the introduction of spores into the oviposition 

 wounds on account of the habit of the insect of closing the wounds 

 with its excreta. 



Experiments to determine the effect of the digestive processes of 

 the insects upon the vitality of the fungus spores gave the following 

 results : — (1) The crickets fed readily on diseased areas of apple and 

 raspberry cane, even when foliage and Aphids were suppHed. (2) 

 When crickets were starved for two days before feeding, spores of 

 various fungi passed through the digestive tract in 6| hours. (3) 

 When crickets were allowed to feed normally before the tests, spores 

 of various fungi, including Sphaeropsis malorum (New York apple 

 canker) and Nummularia discreta (blister canker), were found in the 

 excreta four days after diseased wood ceased to be given as food. 

 (4) Spores of S. malorum and of Coprinus inicacious [sic] showed a high 

 rate of germination after passing through the digestive tract. (5) 

 Attempts to establish S. malorum, the Coniothyrium canker and 

 Sclerotinia fructigena (brown rot) in peaches and apples proved failures 

 except for a slight infection by Coniothyrium in one case. 



