538 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol.8 



of infested plants through the nursery trade and the carrying of spores 

 by wind and rains, or by pickers or workmen in pruning the vines. 

 The suggestion is also made that birds and insects carry the spores 

 to a limited extent. The fact that the blight is so abundant and 

 destructive to raspberries and that, while the tree crickets occur in 

 great numbers on raspberries, they prefer apple wood for oviposition 

 is additional presumptive evidence, tending to support the theory that 

 these insects have a hand in infecting apple trees with the disease. 



Cektain Habits of Tree Crickets which Favor Dissemination 

 OF the Bark Disease 



In the absence of definite data as to the actual part played by the 

 insects in the dissemination of this trouble, it appeared from the start 

 that two habits of tree crickets should be carefully studied, which are, 

 (1) their feeding habits, and (2) their oviposition habits. Tree crickets 

 are omnivorous creatures and subsist on a diet of wide assortment. 

 In their early life they feed extensively on plant lice, leaf-hoppers, 

 tingitids and scale insects. At times they also exhibit cannibalistic 

 tendencies, directing their attacks to the tips of the folded wings or to 

 portions of the abdomens of one another, while those offering feeble 

 resistance may be devoured outright. As the insects approach the 

 mature stage, they develop more pronounced phytophagous and my- 

 cophagous habits, feeding on the floral organs of various plants, on 

 foliage, on fruits of different sorts, and such minute fungi as may be 

 found on bark or decaying vegetation. 



The snowy tree-cricket oviposits in a great variety of plants, among 

 which may be mentioned* apple, plum, cherry, walnut, raspberry, elm, 

 peach, witch hazel, chestnut, butternut, wild crab-apple, hawthorn, 

 red oak, maple and lilac. The largest numbers of eggs have so far 

 been found in apple, plum, cherry and elm. The areas selected for 

 the reception of the eggs varies according to the variety of plant and 

 the age of the wood. With the raspberry, the eggs are inserted at the 

 sides of the buds in the fleshy parts in the axils of the leaves but they 

 do not extend into the pith, while with the elm the eggs may be most 

 commonly observed in the corky areas and they do not as a rule reach 

 the soft inner bark. In the case of other trees, especially the apple, 

 deposition on the smaller branches occurs about the thickened bark 

 at the bases of the twigs. With older wood, the eggs may be found 

 about all areas of the bark, and frequently they are inserted through 

 the lenticels and are placed in the inner soft bark. . In making a hole 

 for the reception of the egg a groove is sometimes cut in the surface 

 of the underlying wood, but the female generally avoids drilling to 

 any appreciable distance in such hard structures. 



