Horidiplosis ficifolii Harris: An Ornamental Fig Pest

California Pest Rating for
Horidiplosis ficifolii: an ornamental fig pest
Horidiplosis ficifolii: an Ornamental Fig Pest
Image Citation: Jakub Beránek
Horidiplosis ficifolii Harris: An Ornamental Fig Pest
Diptera: Cecidomyiidae
Pest Rating: B

Initiating Event:

On November 14, 2014, Dr. Martin Hauser identified Horidiplosis ficifolii on ornamental shrubs in San Diego (PDR 370P06228129). This is the first time this pest has been found in California. A pest rating proposal is needed.

History & Status:

Background: Horidiplosis ficifolii is a gall midge that forms galls on the leaves of ornamental Ficus spp1. Known hosts include Ficus microcarpa1,2, F. retusa2, F. nitida2, and F. panda2. The gall midge may spread long distances when infested host plants are moved.

Worldwide Distribution: Horidiplosis ficifolii is native to China, Taiwan, and Japan. From there it has spread to Florida and greenhouses in Europe.

Official Control: Horidiplosis ficifolii is not known to be under official control in any other states or nations3.

California Distribution: Horidiplosis ficifolii has only been found in San Diego.

California Interceptions: Horidiplosis ficifolii has never been intercepted in regulatory situations in California.

The risk Horidiplosis ficifolii would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Ficus plants are commonly grown in California and Horidiplosis ficifolii is likely to establish where they are grown. The gall midge receives a High (3) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California. Score:

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
– High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Horidiplosis ficifolii is only known to feed on four species of plants in the genus Ficus. It receives a Low (1) in this category.

Evaluate the host range of the pest. Score:

– Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.

3) Pest Dispersal Potential: Gall midges can produce many offspring and may move long distances through commerce in infested host plants. They may also be dispersed locally by wind. Horidiplosis ficifolii receives a High (3) in this category.

Evaluate the natural and artificial dispersal potential of the pest. Score:

– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.

4) Economic Impact: Horidiplosis ficifolii may increase the production cost of Ficus spp. nursery stock and lower the value of infested plants. It is not expected to lower crop yield, trigger lost markets, change cultural practices, vector pestiferous organisms, injure animals, or interfere with water supplies. The gall midge receives a Low (1) in this category.

Evaluate the economic impact of the pest to California using the criteria below. Score:

A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.

– Low (1) causes 0 or 1 of these impacts.
– Medium (2) causes 2 of these impacts.
– High (3) causes 3 or more of these impacts.

5) Environmental Impact: Horidiplosis ficifolii is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. The gall midge is not expected to affect threatened or endangered species or disrupt critical habitats. The gall midge may trigger new treatment programs in the nursery industry and by residents who find infested plants unsightly. Ficus spp. are commonly grown as ornamentals in California and may be significantly affected by this insect.  Horidiplosis ficifolii receives a High (3) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.
B. The pest could directly affect threatened or endangered species.
C. The pest could impact threatened or endangered species by disrupting critical habitats.
D. The pest could trigger additional official or private treatment programs.
E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score:

– Low (1) causes none of the above to occur.
– Medium (2) causes one of the above to occur.
– High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Horidiplosis ficifolii: Medium (11)

Add up the total score and include it here.

– Low = 5-8 points
– Medium = 9-12 points
– High = 13-15 points

6) Post Entry Distribution and Survey Information: Horidiplosis ficifolii is only known from an incursion into San Diego. It receives a Not established (0) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

– Not established (0) Pest never detected in California, or known only from incursions.
– Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
– Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
– High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (11)


There have been no formal surveys for Horidiplosis ficifolii in California. It is possible that the gall midge may be more widespread. However, the species is relatively new to science, it was just described in 2003. It is possible that it may emerge as a more serious pest as it expands its range.

Conclusion and Rating Justification:

Due to its narrow host range the entry of Horidiplosis ficifolii is expected to have limited economic consequences. However, it may have significant environmental impacts by triggering new chemical treatments in the nursery industry and by residents who find infested ornamental plants unsightly. A “B” rating is justified.


1Steck, Gary J. and Scott Krueger. An Ornamental Fig Pest, Horidiplosis ficifolii Harris (Diptera: Cecidomyiidae), Genus and Species New to Florida and North America. Florida Department of Agriculture and Consumer Services. http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Plant-Industry-Publications/Pest-Alerts/Pest-Alerts-An-Ornamental-Fig-Pest-Horidiplosis-Ficifolii-Harris-Diptera-Cecidomyiidae

2Beránek, Jakub and Ivana Šafránková. 2010. First record of Horidiplosis ficifolii Harris 2003 (Diptera: Cecidomyiidae) in the Czech Republic. Plant Protect. Sci. 46(4): 185-187. http://www.agriculturejournals.cz/publicFiles/31854.pdf

3USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/

Responsible Party:

Jason Leathers, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov

 Pest Rating: B

Posted by ls