What is the sticky waste product produced by certain insects that can become a nuisance when present in large amounts?

Honeydew is the sticky waste product secreted by certain insects, particularly sap-sucking pests like aphids and scales. When these insects feed on plant sap, they excrete a sugary substance known as honeydew. This waste can accumulate in significant amounts if the insect population is high, leading to nuisances such as attracting other pests like ants, which are often drawn to honeydew for its sugar content. Additionally, honeydew can promote the growth of sooty mold, a black fungus that can cover plant surfaces and inhibit photosynthesis, further stressing the host plant.

The other options do not fit this context. Inoculum refers to a substance containing microorganisms used to inoculate plants against diseases, horticultural oils are used as pesticides or to improve plant health, and hydraulic sprayers are equipment used to apply pesticides or other substances, none of which produce a sticky waste product like honeydew.