26[7] Pseudaulacaspis pentagona [EIFS

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This leaflet is produced by the Ministry of Agriculture & Livestock, Solomon Islands, with support from IPPSI:
Improved Plant Protection in Solomon Islands, a project financed by ACIAR, the Australian Centre for
International Agricultural Research, Canberra. Authors: Helen Tsatsia, MAL & Grahame Jackson, TerraCircle
Inc.

Extension Fact Sheet 52:

White Peach Scale

Common name: White peach scale

Scientific name: Pseudaulacaspis pentagona

Hosts: Chilli, bell pepper, sliperi kabis, cassava in Solomon Islands. It has also been found
causing heavy infestations on paper mulberry (Broussonetia sp.) on Guadalcanal. Worldwide,
there are many other hosts.

Damage

The scale is most often seen in large numbers on the bottom of stems; there are often so many
that farmers think a white fungus affects the plants (photo, right).

The scale feeds on plant sap, and infestations cause leaves to yellow with a loss of healthy
growth. Fruit size may be reduced and premature drop is likely. Heavy infestations can result
in stunting (cassava), and the death of branches and dieback (chilli and bell pepper). Severe
infestations on cassava have been reported from the weather coast of Guadalcanal.

Biology and Life Cycle

The life cycle, which lasts about 45 days, is complex. Females are covered by a roughly
circular scale (photo, left), about 2-2.5 mm across; beneath the scale is the insect itself, 0.8-
0.9 mm long, pink to yellow, and without legs. Egg laying begins 2 weeks after mating, and

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about 100 eggs are laid over 8-9 days. The first eggs laid become female, those later, male.
Crawlers emerge after 3-4 days of being laid.

The crawlers have three pairs of legs and prominent antennae. The females are more active
and wander further than the males. After about 12 hours they settle down to feed, and go
through two moults before they become adult. The males stay around the mother, moulting
five times, but as adults last only 1 day. They are orange with wings, eyes, legs, long
antennae, but no mouthparts; they do not feed. Their task is to find females and mate,
attracted by chemicals (pheromones) produced by them.

Spread is by crawlers on the wind, and infested cuttings.

Detection and Inspection

Look for the heavy infestations that occur as thick crusts on stems or tree trunks. The leaves
and fruits are not usually infested. The large white colonies of females and males that make
up a heavy infestation are easy to recognize.

Management

Natural enemies:

Species of ladybird beetles and lacewings are known to feed on white peach scale in other
parts of the world and probably these insects do the same in Solomon Islands. Encarsia
diaspidicola, a wasp, has been successfully released in Samoa and more recently in Hawaii
with good results.

Cultural control:

•  Cut out stems of plants infested by white peach scale and burn them
•  Do not plant cuttings from plants infested with white peach scale
•  Avoid planting new crops downwind from those infested with white peach scale, as the

crawlers will spread to the new crop on the wind.

Chemical control:

Insecticides should be avoided, unless control by natural enemies is ineffective. Note, too,
insecticides are not always effective against females; they live under a protective scale.
protected by the scale under which they live.

• Use soap sprays (5 tablespoons of soap in 4 litres water), or white oil (petroleum jelly).

These sprays work by blocking the breathing holes causing suffocation and death. Spray
the stems: the oils must contact the scales. White oil can be obtained as a commercial
product or made by mixing together: 1 cup cooking oil; 2 cups water; 1 teaspoon
dishwashing liquid. Dilute the mixture at 6 teaspoons per litre of water and spray on the
infested parts. The addition of malathion (2 ml/litre water) is useful.

• Use synthetic pyrethroids (for example, lambda cyhalothrin or cypermethrin). These are

useful against crawlers. READ INSTRUCTIONS BEFORE USE.