PEST

NAME
Mealybugs
Various Mealybug Species

ORDER
Hemiptera

FAMILY
Pseudococcidae

Description of the Pest
Adult females are 3-5mm long, flattened oval-shaped white insects, which secrete a white, mealy wax that forms a row of hair-like filaments of fairly uniform length around the edge of the body; the hind end bears one or two pairs of filaments that are longer than the others. They are mobile but slow-moving. The seldom-seen adult males are tiny winged insects with a pair of long waxy tail filaments. Early stage nymphs are tiny, pink and mobile; later stages resemble adult females.

     

There are many types of mealybugs including;

•      Longtailed Mealybugs(Pseudococcus longispinus) generally have tail filaments that are longer than there body. If squashed yellow body fluid is revealed and the eggs are laid under the body and normally hatch immediately.
  
  
  •      Citrus Mealybug(Planococcus citri). This insect has tail filaments that are less than 1/3 the length of its body. It produces yellow orange body fluid and lays eggs in a cottony mass.
    
    
    •      Citrophilous Mealybug( Pseudococcus calceolariae). This insect has tail filaments that are about 1/3 the length of its body. It produces dark red body fluid and the eggs are laid in a cottony sac.
      
      
      •      Root Mealybug(Rhizeocusfalcifer). This insect is not normally seen but produces a open white mass as it feeds on the outer or terminal roots, normally container plants, particularly cacti species. The eggs are laid in the waxy mass and adults may dispersed by ants.
        
        
        •      Hibiscus Mealybug(Maconellicoccus hirsutus)
          
          •      Tuber Mealybug(Pseudococcus affinis)
            
            The Mealybugs(Pseudococcus adonidum) and (Planococcus citri) are a major pest of cactispecies, sucking sap and turning the infected area yellow. These pests are also found on Strelitzia, Camelliaand Yuccaspecies.
            
            Appearance and Distribution of the Pest
            Mealy bugs are found worldwide. The above ground species are found in sheltered areas such as under a leaf or in leaf bases. They are also found where two fruits or leaves touch and are not readily noticeable.
            
            The below ground species are only found when a plant is re-potted or the infected plant wilts and dies. Mealybugs are distributed several ways including slowly walking to a new host or transferred on clothing, contaminated plants or strong wind and on visiting insects. They are also farmed by ants which in a nursery situation infest pots by tunnelling and carrying mealybugs to the roots.
            
            Attending Ants
            
            Life Cycle
            These insects have a Hemimetabolouslife cycle, ie. When the immature nymphsresemble the adults.
            Up to 200 young are produced in 2-3 weeks; eggs may hatch as they are being laid. The life cycle includes eggs, nymphs (3 to 4 stages) to adult takes 6 weeks, in warmer months; several generations appear throughout the year.
            
            Period of Activity
            Active all year, particularly in spring and autumn. Warm, humid conditions are preferred and the insect overwinter outdoors as eggs. These may be found on surrounding weeds. In Citrus species many longtailed mealybugs overwinter as juveniles, maturing during spring. In a Glasshouse conditions mealybugs are active through the year.
            
            Damage Caused
            Adults and nymphs suck sap, congregating in sheltered parts of the plants; some species feed undetected on roots. Early infestations may go unnoticed until the plant begins to wilt. The insect also produces honeydew, which gives rise to sooty mould.
            
                 Clivia miniata
            
            Susceptible Plants
            Mealybugs are found on a wide variety of trees and shrubs. They are also destructive to many ornamentals; including indoor plants (especially African violets and ferns), and are a major greenhouse pest.
            
            Aglaonemaspecies are infected by mealybugs that form masses in the leaf axils and on the underside of the leaves or on roots. The plants become stunted and the foliage starts to die off. Indoor or plants grown under glass are particularly susceptible.
            
            Cactus species
            Many species of mealybug are common pest of cactus and succulents. The small, grey to light brown mealy bugs are difficult to see amongst the spines. Nesting females appear as the small balls of white fluff on cactus spines or around the base and under the rim of the pots. The female will produce eggs or living nymphs and the insect will produce honeydew that attracts ants. Ants should be discouraged as they farm mealy bugs, moving them from one place to another in a cactus collection.
            Cactus is also attacked by the root mealybugsthat infest the roots of plants and their damage allows fungal and bacterial infections to enter the plant tissue. They can be identified by white fluffy deposits in the soil or underneath a pot and appeared as tiny pinkish brown wood lice up to 3 mm long.
            
            Catalpa species are susceptible to the mealybug (Pseudococcus comstocki)which is a wax covered mealybug that causes distorted growth of the branches and branchlets.
            
            Fernspecies are commonly attacked by mealy bugs and can be recognised by small white, waxy secretions as it feeds in the crevices at vein junctions or on the exposed rhizome.
            
            Hederaand Crassulaspecies are susceptible to three species of mealybugs including Citrus Mealybug(Planococcus citri) and not normally requiring control.
            
            Laburnum anagyroidesis infested with the Grape Mealybug(Pseudococcus maritimus) infesting the branches and twigs.
            
            Plumeria acutifoliabecomes infested with mealybugs on the new growth but normally control is not required.
            
            Psidiumspecies are attacked by the Longtailed Mealybugs(Pseudococcus longispinus).
            
            Sequoiaspecies are attacked by three species of Mealybugs including (Planococcus citri).
            
            Thymusspecies are attacked by the Root Mealybug(Rhizeocusfalcifer).
            
            Thujaspecies Cupressus macrocarpaand Araucaria heterophyllaare can be infested with the mealybugs (Pseudococcus ryani).
            
            Turf Grassmay be infested with mealybugs causing severs damage and often go undetected and build up large colonies quickly. The turf forms brown dry patches and looks simular to Dollar Spot the infestation may also occur around core holes and can be discouraged by generous watering. Agrostis palustris(Bent) and Cynodonspecies (Couch) are commonly attacked.
            
            Yuccaspecies are attacked by the mealybug (Planococcus citri).
            
            Cultural Control
            Small plants may be sprayed with a soapy water solution or sponged down preferably during the evening. Heavily infected areas should be pruned and destroyed or the whole plant removed. Infested pot-plants should be discarded and thoroughly disinfect pots before recycling). Maintain vigour by watering to replace sap loss, this helps infected plants to recover.
            As a preventative measure for root mealybugs grind up mothballs and add them to the potting mix to discourage infestations. Care should be taken as the chemicals in mothballs can damage plastic pots (use clay pots) and in some countries such as the UK. mothballs must be used as directed on the label.
            
            BiologicalControl
            Lacewing and ladybeetle larvae (Cryptolaemus montrouzeri) control small infestations. This predator insect requires temperatures of at least 21° C. (70°F) and in small infestations it is difficult to maintain a balance between predator and prey.
            
            
            Ladybird beetle larvae eats Mealybugs            Ladybird beetle up to 4 mm long
            
            Chemical Control
            Spray with white oil may have an effect on the population or spray Omethoate. Contact insecticides are usually ineffective because of the insect`s protective waxy coating.
            Note
            Always read the label for registration details and direction of use prior to application of any chemicals.