Fall

Why do trees lose their leaves in fall?

Deciduous trees drop their leaves every fall to protect the tree from heavy snow and loss of water. Due to cold winds, leaves can dry out and easily become fragile or frozen. Leaves have a delicate cellular structure and ice crystals can destroy their cell walls. A tree without leaves also has less surface area on which snow can accumulate, reducing the risk of damage and broken limbs.

Dozens of ladybugs have invaded my house. They cluster in the corners, crash into light fixtures and windows, and crawl across the furniture. Where do they come from? Will they hurt my children or damage my house?

There are 475 native North American species of ladybird beetles or ladybugs. All of these except two species are very beneficial insects that eat aphids, scale insects, other injurious insects, and mites. Native ladybugs hibernate as adults in aggregations under logs, leaves, rocks, or in debris. These native species do not invade your house.

The ladybugs in your house are Asian multicolored lady beetles that were accidentally introduced into New Orleans in 1988 from an Asian freighter in port. They quickly spread throughout much of the United States. In fall, they search for refuge from the cold and enter houses through cracks in foundations, in crevices around uncaulked windows, or other small openings. Like many other nonnative species, they are aggressively successful, prolific breeders, and generalist feeders.

Although they may be a pest when they invade your house, they are very beneficial to plants. One beetle larva may eat 300 aphids before it becomes an adult, dining on any of 50 species of aphids. These beetles have a very beneficial effect on roses, trees, fruit-bearing plants, and especially on pecan trees where they have nearly eliminated the need for chemical control of aphid pests in Southeast pecan groves.

The Asian ladybug does not cause disease, nor does it eat wood or food. If the insects get behind walls, do not spray with insecticides because the dead insects will attract mice and cause an unpleasant odor. The best control is to use a hand vacuum cleaner to sweep up clusters of insects and release them outside. Seal all caulking and cracks in your house. Try to remember that these are overall very beneficial insects.

Why are so many deer killed by cars in fall?

Deer are “blinded by love” in the fall. Locally, mating season begins in September with peak activity in mid-November. Male deer (bucks) spend autumn marking their territory, following the scent of females (does), and fighting with each other over the right to mate. Often a doe will flee across the road with a buck in pursuit, both oblivious to passing cars. In the process many are hit. No matter what season, use caution when driving near fields and woodlands, particularly at dawn and dusk when deer are most active. If you see a deer cross the road, slow down because others may follow. By mid-winter, bucks have dropped their antlers and deer of both sexes become preoccupied with finding food sources. Most fawns (babies) are born in May or June, depending on when the doe was bred.