Dianne Zimmerman, age 11, of Eureka, Illinois, for her question:
How does a worm get inside an apple?
This maggoty menace usually enters a baby green apple soon after the petal pink blossoms have fallen The apple grows and ripens around it while the wormy grub inside gorges himself to the full. Sometimes, but not always, he departs before the apple orchards are harvested.
Our orchards provide homes for a wide variety of greedy grubs and at least two types plunder the fruit of the apple tree. The apple worm, alias the codling moth, may be a pest in any orchard from coast to coast. The adult female is a dainty moth, less than half an inch long, streaked with pastel blues and brown with a round eye of brown and yellow on each tip. Her back wings are veined and bordered with blended tones of cream and cinnamon. If you spot her fluttering around your apple tree, have no mercy.
She is looking for a suitable place to lay her eggs where her newly hatched offspring will find a handy supply of their favorite food. She lays her first batch of eggs during or soon after apple blossom time, when the orchard boughs are dressed in their petal pink finery. The eggs look like white pinpoints, too small to notice, and the codling moth deposits them one by one on the underside of a young green apple leaf. The eggs hatch into miniature maggots with dark heads.
Somehow they sense that a supply of their favorite food is nearby and off they crawl to the grocery store. Each one finds a baby green apple about three or four weeks old. His jaws are strong enough to pierce its tender skin. But as a rule he attacks at the weakest spot. This is the end opposite the stalk, where the apple blossom recently bloomed. He chews his way into the young apple, eating out a tunnel on his way to the core. The apple is now his secret home, a pantry stuffed with his favorite food.
As the apple grows bigger, the greedy grub grows with him. He gorges himself on the chewy pulp, filling the cavities with messy brown wastes. You may not notice his tiny entrance but the pasty, black faced grub may be there when you bite into the apple. When he grows a quarter inch long, he is ready to leave the rotten mess inside the apple and crawl outdoors. Then he sleeps through his pupa stage in a crevice in the tree bark.
The apple maggot, alias the railroad worm, attacks our northern orchards. His mother is a fly who punctures the skin of the sweetest type of apple and lays her tiny white oval eggs right inside. The larva is a pasty white grub with a tapering body and no legs. He gorges on the pulp of the growing apple, leaving pockets of crumby brown rot. The small, rot filled puncture may be seen on the skin of the ripe apple. But often this maggoty menace totally ruins the ripening apple and it drops from the tree before harvest time.
In northern orchards, the pupae of the first batch of codling moths become winged adults in July. They infest the fruit with grubs that are still inside when the ripe apples go to market. To southern orchards, a third generation may attack before harvest time. The season's last batch of codling moth pupae hibernates through the winter in the soil. The pupae of the apple maggot also winter in the soil. Both of these orchard pests become winged adults in time to infest the baby fruit soon after apple blossom time.