. Manual of fruit insects. to fruits, oftenworking in the same orchards, the term canker-worm is restrictedto the two distinct species recognized in 1873 and then giventhe common names of the spring canker-worm and the fallcanker-worm. Both of these native species often occur together in injuriousnumbers in the same locality. The apple and elm are favoritefood-plants, although several other fruit and shade trees areoften attacked. The caterpillars appear on the trees in earlyspring and work mostly during May, skeletonizing the leaves,which soon turn brown. In June badly infested trees or or-ch
. Manual of fruit insects. to fruits, oftenworking in the same orchards, the term canker-worm is restrictedto the two distinct species recognized in 1873 and then giventhe common names of the spring canker-worm and the fallcanker-worm. Both of these native species often occur together in injuriousnumbers in the same locality. The apple and elm are favoritefood-plants, although several other fruit and shade trees areoften attacked. The caterpillars appear on the trees in earlyspring and work mostly during May, skeletonizing the leaves,which soon turn brown. In June badly infested trees or or-chards often appear from a distance as though a fire had swept 78 FRUIT INSECTS through them. Like many other insect pests, canker-wormshave their ups and downs, or periods of increase and de-crease. Usually their destructive period lasts from 3 to 5years or more before their enemies and climatic conditionssucceed in bringing about the do^\Ti period, which may last10 or more years. The defoliated trees grow weaker each year,. Fig. bO. Canker-worm moths cau^lit on sticky band while ascending treetrunk. mature but little fruit, and may finally succumb to the ravagesof the hordes of canker-worms. If disturl)ed, the caterpillarsoften cling with their hind pro-legs and stand out straight, stiffand motionless, this strange attitude giving them a protectiveresemblance to the smaller twigs or leaf-stems ; or they maydrop suddenly and swing suspended in the air by a silken corduntil the threatened danger has apparently passed, when they APPLE INSECTS — BUDS AND FOLIAGE 79 resume their normal looping positions or ascend their ropessomewhat sailor-fashion. The male canker-worm moths have fully developed wings,while the females are practically wingless, only short stubs ofwings being present. This lack of wings renders it necessaryfor the females to crawl up the trees to lay their eggs, and affordsan opportunity to apply certain effective barrier remedialmeasures (Fig. 80). The moths are a
Size: 1739px × 1437px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectbenefic, bookyear1915
