. Manual of fruit insects. le borer may oiten girdle the trunk and kill smalltrees. The full-grown, light-yellow, legless grub is about aninch long with its second thoracic segment much broadened andflattened (Fig. 187). On the upper and lower surfaces of thissegment are large, roughened spots with two smooth diverginglinear depressions extending through the dorsal spot and onemedially through the ventral spot. The grub habitually restsin a curved position and gets its full growth during a singlesummer. It finally extends its burrow outward nearly throughthe bark, then digs a little deeper int
. Manual of fruit insects. le borer may oiten girdle the trunk and kill smalltrees. The full-grown, light-yellow, legless grub is about aninch long with its second thoracic segment much broadened andflattened (Fig. 187). On the upper and lower surfaces of thissegment are large, roughened spots with two smooth diverginglinear depressions extending through the dorsal spot and onemedially through the ventral spot. The grub habitually restsin a curved position and gets its full growth during a singlesummer. It finally extends its burrow outward nearly throughthe bark, then digs a little deeper into the solid wood, forminga chamber in which it transforms through the tender whitepupal stage (Fig. 188) to the adult insect. In the north thesepupal chambers are made in the spring, the winter monthsb(nng passed as grubs, but farther south pupation may occurin November, the pupse hibernating. The pupal period lastsabout three weeks in the spring, and the beetles cut their way APPLE INSECTS — BORERS AND MISCELLANEOUS 197. Fig. 188. — Pupa ofthe flat-headed apple-tree borer. out through an eUiptical hole. Thus this flat-headed borerhas a much shorter hfe-cycle than the round-headed species,from which it also differs much in all itsstages and in its habits. Although snugly hidden in its bur-row beneath the bark, this flat-headedborer does not escape from natural ene-mies. Woodpeckers and ants devourmany of the grubs and pupae and the fol-lowing parasites prey upon it: the Braco-nids, Bracon charus and pedinator, Spa-thius pallidus; the Ichneumonids, Lahenaapicalis and grallator; and one or morespecies of Chalcids. Remedial suggestions. As healthy, well-established trees are rarely attacked by thisborer, its ravages can be largely prevented by keeping youngtrees in a thrifty, growing condition. Many of the suggestionsfor controlling the round-headed borer are also appUcable tothis species. The deterrent soap and emulsion washes and pro-tective coverings have been found effecti
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbenefic, bookyear1915
