Technical agronomist and InSense owner Russell Fox says the longtailed mealybug LTMB (Pseudococcus longispinus) is proving to be not just a very persistent pest – it is also a pest on the increase in many areas and crops. 

InSense specialises in protection of fruit and vegetables, particularly in harsh and extreme weather conditions.

Mr Fox said the LTMB is difficult to control because this particular mealybug does not produce the usual egg masses. 

Instead, he said, there is no visible egg stage in its reproductive cycle as its nymphs hatch immediately upon oviposition (laying) making it seem to be laying live nymphs.

From there the emergence of the nymphs continues across a long period, especially in spring, where variable weather conditions also make timing and frequency of chemical applications difficult. 

The Female  

The female is easy to see and identify and is a common pest, especially in persimmons.

This mealybug gets its common name from the two long, waxy filaments protruding from the last abdominal segment of adult females.

The Nymphs 

Female longtailed mealybug nymphs undergo three instars (growth stages) before reaching adulthood, whereas males undergo four growth stages.

By the second instar, the nymphs have the white, waxy coating characteristic of mealybugs making chemical control difficult. 

The males feed only during the first and second instars.

Female nymphs feed throughout all instars. 

The Male. 

The LTMB is a sexually dimorphic species, meaning the male and female do not look alike. 

Male adults are winged. They are not as commonly seen or monitored as the female mealybugs, as they do not feed on the host plant. 

Adult males do not feed and live only a few days, while females can live as long as three months.

There are pheromone lures that attract the male mealybug, that can be very useful in monitoring the lifecycle and presence on this pest.  

However, at a practical level, the monitoring of the adult is quite difficult.

They are small about 2mm long and look like a gnat or very small wasp. 

The longtailed mealybug has a relatively wide host range including many economically important crops such as avocado, citrus, grapes, pear, persimmon, and pineapple (Faber et al. 2007, Furness 1976, Dentener et al. 1997, Williams and Watson 1988).

Valuable ornamental plants, especially those adapted to tropical and subtropical environments, are also hosts.

These include species of cycads (Culbert 1995) and orchids (Kot et al. 2015, Ray and Hoy 2014).

Plants kept inside homes or in greenhouses seem to be especially at risk for mealybug infestation, due to the relatively stable temperature and humidity of these environments (Blumberg and Van Driesche 2001).

Mealybugs and other insects with piercing-sucking mouthparts, like aphids, feed directly from the host plant vascular system.

This food source is plentiful but somewhat dilute, meaning the insect must take in an abundance of plant sap to get adequate nutrition.

Honeydew, a sugary substance periodically excreted from the insect’s body, is a waste product of this feeding behaviour.

Honeydew itself is not harmful to the plant but can coat the leaves and nearby objects and encourage growth of a fungus known as sooty mould.

Sooty mould, like honeydew, is not directly injurious to the plant, but it is unsightly, hard to remove, and can diminish the plant’s photosynthetic capabilities.

It also reduces or eliminates the economic value of fruits grown for fresh consumption and plants grown for ornamental value.