To protect its eggs from wandering ants, a lacewing fly first lets a thread drop from its abdomen onto a leaf. This thread hardens into a stalk, on top of which the insect mother deposits a single egg. Often a number of stalks twine together, making a sort of “egg tree,” which keeps the eggs off the surface of the leaf.
The ichneumon wasp deposits her eggs deep in the flesh of some other live, tasty insect, using her spear-like ovipositor (a special egg-laying organ). When the eggs hatch, the baby wasps (larvae) immediately begin to eat the insides of the host and to use the empty skin of the prey as a house in which to develop.
Trees and plants develop small bumps resembling the pimples or boils on human skin. These bumps can be caused by bacteria or viruses, molds, mites, or round worms. But a great many are caused by insects — beetles, moths, aphids, thrips, flies, and wasps. These insects plant their eggs in the plant or tree, and the resulting “gall” provides a home, protection, and food for the developing creature within.
Spiders have six pairs of glands, each of which independently spins silk threads through tiny bumps on the spider's abdomen. These bumps are probably remains of what at one time were legs in spider ancestors. Although all the glands produce silk, the silk from each pair differs.
Certain solitary wasps build their nests of mud, earth, or even in tunnels bored in wood. They lay their eggs and stock their nests with an insect which has been paralyzed by their sting. The nest is then closed off. When the eggs hatch, the infant larvae feed off the fresh insect food.