It is rather unlikely that this can ever be known, but there exists three possibilities for its entry into our country namely:
Carried by wind over long distances
Accidental entry by boat or by plane
Smuggling of an infested seedling or twig into the country
Damage
Adults range from 2-5 millimetres long and are dark-coloured, long-legged insects. Both winged and wingless forms occur but the latter one is most common.
Adult aphid on cypress twig The aphid feeds on a wide range of sites varying from green to woody stems. Damage mainly occurs by sap feeding hence causing yellowing and browning of foliage.
Feeding retards new growth and causes desiccation of the stems and a progressive dieback of heavily infested trees.
Large amount of honeydew is also produced by the aphid, thereby acting as medium for growth of sooty mould and hence reducing photosynthesis and gas exchange.
In other countries, severe economic damage is caused by the aphid in commercial plantations. Locally, it affects the aesthetic value of our cypress and is the cause for the death of many trees.
Management of CYPRESS APHIDS
Several approaches such as biological, genetic, silvicultural and chemical control are being employed in many countries for managing the pest. The best strategy is one which is ecologically and economically efficient and socially accepted.
Biolgical Control Approach
Several natural enemies have been observed locally namely lacewings, ladybirds, hoverflies and spiders, but these are generalist biological control agents and their action is not significant enough to exert sufficient control over the aphids.
A parasitic wasp, Pauesia juniperorum has given promising results in other cypress growing countries to control the pest.
The adult is about 10 mm long with a black head, brown-black thorax, yellow legs and a yellowish abdomen which becomes darker in older insects.
This parasitoid was imported from Kenya. In 2003, 2004 and 2005 the biocontrol agent was released in several regions.
The biological control agent was observed in the field several months after release. It is expected that successful establishment will be attained after several releases. More parasitoids will be imported and released during 2006.
Advice to People owing Cypress Trees
Observing if aphids are present
Watering of trees during dry periods
Trimming of dead branches
Hand picking of aphids for small plants
Planting of other species of cypress, eg. Thuja spp
Apiculture