Curculios come out of woodwork to attack fruit trees

By Lee Reich
The Associated Press

With warm weather comes plum curculios, swooping in hordes out of nearby woods onto plum, peach, cherry, apple, and apricot trees.

Curculios are insects, and they are hungry as they come out of hibernation. But it is their egg-laying, evidenced by telltale, crescent-shaped scars, that causes the real problems.

Any fruit with an egg in it is likely to drop before ripe. Stung cherries commonly stay on the tree, though, as do peaches in which eggs have been laid a bit later in the season. But in these cases, you end up with wormy fruits.

Plum curculios finish laying their eggs about six weeks after blossoms fall. The larvae fall to the ground with the fruit, then burrow into the soil, become adults, emerge from the soil after brief feeding, and finally seek winter quarters in nearby leaf-covered, wooded ground.

If we could look beyond the evildoings of plum curculio, we would see quite a cute little bugger. The quarter-inch long, brown insect looks very much like a miniature buffalo.

Cute as it is, this pest is a bugaboo to anyone trying to grow tree fruits without spraying synthetic pesticides. For over a hundred years, numerous offbeat and not-so-offbeat remedies have been suggested, from hanging corncobs soaked in kerosene in the trees, to packing hard the soil beneath the trees, to penning chickens or pigs around the trees, and even just picking up and burning all fallen ones.

The most universally suggested remedy in old books capitalized on the curculio’s habit of faking death when disturbed. The advice was to jar the tree with a padded mallet and catch, then destroy, the curculios that fall on a sheet spread on the ground. The curculios put on their death act longer in cool weather, so early morning, or evening, were suggested “show times.” Jarring would not be effective unless religiously practiced every day, preferably twice a day, during the approximately six weeks the curculio is active.

Until some Achilles’ heel is found in the curculios’ habits, insecticidal sprays are the most feasible and reliable control. A new, nontoxic clay spray, called Surround, offers hope if sprayed weekly.