• Gall wasps lay eggs in lemon trees and cause galls.Jupiterimages/liquidlibrary/Getty Images
  
  Citrus gall wasps lay eggs in twigs or branches of lemon trees, which causes the trees to develop galls (unsightly swellings). The wasps live in Australia and affect other types of citrus trees too. Lemon tree owners have limited treatment options for gall problems, but they can usually get rid of infestations.
  
  

Gall Removal

• Gardeners can physically cut off galls containing wasp eggs, according to ABC and the New South Wales Government Industry and Investment Department. Cutting off the galls removes the wasp eggs and makes it impossible for the wasp population to continue to grow. The only problems with this removal method are that it can be difficult to reach galls on all parts of a large tree and that the wasps can keep returning if they live on other trees nearby.
  
  

Branch Removal

• The New South Wales Government Industry and Investment Department suggests that gardeners remove entire infected shoots and branches rather than just the galls themselves in some situations. Removing badly infected branches helps keep the tree healthy, since the galls damage branches and make them less productive. If adult wasps have already hatched, removing damaged branches also helps get rid of weakened areas for the new wasps to lay more eggs.
  
  

Natural Predators

• Introducing parasitic wasps to kill of citrus gall wasps provides the most effective and natural long-term gall treatment for lemon trees. The New South Wales Government Industry and Investment Department recommends Megastigmus brevivalus and M. trisulcus wasps as predators that reduce citrus gall wasp populations. It suggests a supplier called "Bugs for Bugs" as the only supplier in Australia for predatory wasps. Gardeners should release parasitic wasps three to four weeks after gall wasps hatch.
  
  

Chemical Treatment

• Some large orchards use the pesticide Supracide to control gall wasps. However, the New South Wales Government Industry and Investment Department warns that this pesticide interferes with the use of parasitic wasp treatments. Growers also have difficulties timing the pesticide applications. In general, only commercial orchards use the pesticide and only for severe infections requiring quick treatment.