Citrus Gall Wasp

The Citrus gall wasp (Bruchophagus fellis), is a native insect pest of Australia that feeds on the Australian finger lime or Citrus australasica. Traditionally, it has infested citrus trees in the regions of Queensland and the central and norther coast of NSW, but it is now found inland and as far south as Victoria. Recently, even backyard trees planted in Griffith City, Sunraysia, and the Riverland areas found it troublesome.

Characteristics of the Citrus Gall Wasp

All citrus plants are susceptible to attacks from the citrus gall wasp, however lemons, grapefruit and oranges seem to be the first affected. Easily identify the infestation of these pests by familiarizing yourself with its characteristics as listed below:
  1. Adult citrus gall wasps are small shiny-black wasps about 2.5 mm in length
  2. red tinted eyes which covers most of the regions of its head
  3. brown translucent wings
  4. What out for these wasp in late September early October.

Symptoms of Plants Infected with Citrus Gall Wasp

The damaged caused by the Citrus Gall Wasp begins when the female citrus gall wasp starts laying its eggs on the new seasons flush of the citrus trees. It will take it only two to four weeks to hatch before the larvae burrow into the branches of the citrus plants for nine to ten months. When this happens, you will notice swelling of stems that leads to the formation of small galls or pockets on your plants.

Seasonal Damage of the Citrus Gall Wasp

The Citrus Gall Wasp matures and emerges from the stems during late September (later in southern districts). After mating, the females immediately lay eggs onto the new season flush. Eggs hatch after 2 - 4 weeks and the young larvae burrow into the bark.

Citrus Gall Wasp Control

If this is not properly addressed, then it is very much possible that your plant will lose its vigor and die. You may choose to use one of the following methods to help eliminate these pests from your trees: Chemical Control Methidathion or Supracide are the only chemicals that are registered to help control the spread and growth of the Citrus Gall Wasp. Sprayed onto the affected plants will help control its growth, nevertheless it will not completely eliminate these pests on your plants. Typically, this treatment is applied on the trees for four weeks to guarantee that these pests will not mature and spread further damage on your citrus plants. It is also used in conjunction with cultural control methods. Cultural Control The best time to eliminate these pests are before they emerge from last years laying or before they lay their new eggs. To help reduce the infestation of the citrus gall wasp, use the following cultural approaches:
  1. Prune any affected branched and place them in a air tight container in the garbage.
  2. Thin out the foliage of your trees so pests are more visible when present, this will also avoid moisture build up amongst the foliage.
  3. Reduced amount of fertilizer as research shows that those with high fertilizer seem to attract more citrus gall wasps
  4. reduced use of under-tree sprinklers because higher humidity attracts the growth and spread of these wasps
Biological Control Use of parasites and predators may also be used to control the growth and production of the citrus gall wasp. These include the following:
  1. Megastigmus brevivalvus
  2. M. trisulcus
Bugs for Bugs located in Munduberra, Queensland is the only commercial of parasitoids that will help naturally eliminate these pests from your citrus plants. However, this comes in limited supplies and is only available during late October until early November. It is best to request this in advance from them if you do intend to safeguard your plants from these types of infestations.

Prevention and Monitoring of the Citrus Gall Wasp

It is highly recommended that you check your plants on a regular basis to avoid an infestation. This is the best preventive measure one can do in order to help rid your plants from these pests. This informative article was written from our own research and development, by our horticulturalists and industry professionals here at eplants.