Q. I want to buy beneficial insects. Where can I find them, and what insects besides ladybugs are good to add in the Houston area? M.B., Pearland

A. Some local nurseries carry beneficials; ask your nurseryman about availability. Mail-order companies such as Gardens Alive, www.gardensalive.com, also sell beneficials. Follow package instructions; release time and temperature are important.

There two kinds of beneficial insects: predators and parasitoids. Predators, such as ladybugs and assassin bugs, devour their prey. Parasitoids, such as Trichogramma wasps, lay their eggs on the enemy. When the eggs hatch, the larvae eat the unwanted insect. Green lacewings, like ladybugs, diminish aphid and mealybug populations, as well as thrips. Other beneficials include damsel bugs, ground beetles, hover flies and beneficial nematodes. Plant members of the daisy family, cosmos and yarrow to encourage beneficials. They need pollen and nectar.