For example, you may wish to identify the type of insect that is developing as a borer in a log. Although you could extract the larvae, they must remain within the log if you wish it to transform to the adult stage. All insects that feed on the sap of plants, such as aphids or scales, will not survive long once the plant has been cut and no longer can provide the flow of sap they need. Even insects that chew leaves, such as caterpillars and beetle larvae, may do poorly on picked leaves if the leaves dry out too rapidly. Finally there are some insects that may have attached themselves firmly to the plant and would be injured if removed.
Inthese cases rear the insect by covering the plant in place.
For example a simple sleeve cage consists of making a mesh fabric sleeve that slips over the branch and is tied at both ends to prevent the insects from escaping. When rearing larger insects that might chew through fabric, such as a wood boring beetle, the cage should be made of a sturdier wire mesh. Substrate and shelter. Some sort of shelter is usually needed by insects, particularly those that are active at night and seek dark protected areas during the day. Pieces of bark or rocks are good natural materials for insect cover.