Citrus Mealybugs are a little sap-sucking insect, Grey in colour with a white dusty wax covering. Tend to affect glasshouse plants or houseplants as they require warm temperatures to survive. They tend to live together in dense groups, in protected parts of plants. As they suck large amounts of sap from plants, to gain sufficient nutrition, they produce a sticky sugary substance, called honeydew. This honeydew falls on to the leaves below infestation and a grey mould called Sooty mould may develop. This mould may reduce the plants ability to photosynthesise.