Bronze Bug | Thaumastocoris peregrinus Carpintero and Dellapé

Bronze Bug
California Pest Rating for
Thaumastocoris peregrinus Carpintero and Dellapé: Bronze Bug
Hemiptera: Thaumastocoridae
Pest Rating:  B

Initiating Event:

In the summer of 2016 residents of Los Angeles County began to observe infestations of an unusual bug and shared images online1.  The images were tentatively labeled as Thaumastocoris peregrinus, an insect not known to be found in North America.  Staff from Los Angeles County collected official specimens in follow-up surveys.  The diagnosis was confirmed on July 29 (PDR 190P06060169).  A pest rating proposal is required to determine a permanent pest rating.

History & Status:

Background:  Thaumastocoris peregrinus is a sap-sucking insect that feeds on several dozen species of Eucalyptus and Corymbia1.  Infestations of the insect can lead to leaf loss, thinning tree canopies, and branch dieback1.  The bugs can be transported long distances when plants or fresh plant parts are moved.

Worldwide Distribution: Thaumastocoris peregrinus is thought to be native to Australia.  From there it has spread to New Zealand2, southern Africa2, southern South America2, Italy2, Portugal2, and Mexico4.

Official Control: Thaumastocoris peregrinus is listed as a harmful organism by Peru3.

California Distribution:  Thaumastocoris peregrinus has only been found in Los Angeles County.

California Interceptions Thaumastocoris peregrinus has never been found in any regulatory situations in California.

The risk Thaumastocoris peregrinus (bronze bug) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Eucalyptus trees are grown throughout much of California and Thaumastocoris peregrinus is likely to establish wherever they grow. It 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: Thaumastocoris peregrinus feeds on several dozen species of plants in two genera in one plant family.  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: Thaumastocoris peregrinus has a high reproductive rate.  Each female lays an average of 60 eggs and can mature from egg to adult in 20 days2.  The insects can spread locally by crawling, by wind, or by hitchhiking on animals, clothing, or equipment.  They can also be transported long distances when infested plants or fresh plant parts are moved.  Bronze bug 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: Thaumastocoris peregrinus is not expected to lower any crop yields in California.  It may increase the production costs of Eucalyptus and Corymbia nursery stock.  Its presence may also disrupt commerce in nursery stock.  Bronze bug is not expected to change cultural practices, vector other organisms, injure animals, or interfere with water supplies.  It receives a Medium (2) 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: Thaumastocoris peregrinus is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes.  It is not expected to affect threatened or endangered species or disrupt critical habitats.  Bronze bug might trigger additional chemical treatment of Eucalyptus and Corymbria in the nursery industry and by residents who find infested plants unsightly.  Eucalyptus trees are common ornamental plants and are likely to be significantly affected by this pest.  Thaumastocoris peregrinus 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 Thaumastocoris peregrinus (Bronze Bug):  Medium (12)

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: Thaumastocoris peregrinus is only known to be established in Los Angeles County. It receives a Low (-1) 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 not been any official surveys for Thaumastocoris peregrinus in California.  It could be more widespread.

Conclusion and Rating Justification:

Thaumastocoris peregrinus appears to be established in Los Angeles County and is not under official control.  Its establishment in the state is likely to have significant economic impacts to nurseries that produce and distribute Corymbia and Eucalyptus plants.  It is also likely to have environmental impacts as it triggers new chemical treatments and significantly affects ornamental plantings.  A “B” rating is justified.



2  CABI Invasive Species Compendium

3  USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD).

4 Jiménez-Quiroz, Eduardo, Juan Manuel Vanegas-Rico, Oscar Morales-Martínez, Refugio Lomeli-Flores, and Esteban Rodríguez-Leyva. 2016.  First Record of the Bronze Bug, Thaumastocoris peregrinus Carpintero & Dellapé 2006 (Hemiptera: Thaumastocoridae), in Mexico. Journal of Agricultural and Urban Entomology 32(1):35-39.

Responsible Party:

Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211,[@]

Pest Rating:  B

Posted by ls