Matthew R. Moore, James P. Cuda, Paul D. Pratt, and Min B. Rayamajhi
1. This document is EENY655, one of a series of the Department of Entomology and Nematology, UF/IFAS Extension. Original publication date July 2016.
2. Matthew R. Moore; James P. Cuda, professor; Paul D. Pratt, adjunct assistant; and Min B. Rayamajhi, assistant scientist; Department of Entomology and
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U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County
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The melaleuca gall midge, Lophodiplosis trifida Gagné, is a
natural enemy of the invasive plant melaleuca (Australian
broadleaved paperbark), Melaleuca quinquenervia (Cav.)
S.T. Blake (Myrtales: Myrtaceae) in Florida (Figure 1). This
species’ ability to form galls on and damage melaleuca trees
led to its study as a possible biological control agent and its
eventual release in the United States.
The melaleuca gall midge is native to eastern coastal areas
of Queensland and New South Wales in Australia (Gagné
et al. 1997; Gagné 2010). Specifically, the melaleuca gall
midge has been collected near the towns of Tully and
Woodburn, Roy’s Road, and the Brisbane suburb of
Indooroopilly (Gagné et al. 1997; Goolsby et al. 2002;
Gagné 2010; Wineriter Wright and Center 2008) (Figure
2). In 2008, the melaleuca gall midge was approved for field
release into Florida. It was subsequently released at 24 sites
across southern Florida in 13 counties (Broward, Charlotte,
Collier, Hendry, Hillsborough, Lee, Martin, Miami-Dade,
Orange, Palm Beach, Polk, Sarasota, and St. Lucie) (USDA
2008; Pratt et al. 2013) (Figure 3). The released melaleuca
gall midges survived at all release locations except one, due
to a freeze at the site (Pratt et al. 2013). This locality was
recolonized by melaleuca gall midges from nearby areas
and the midge has subsequently spread to other areas in
Florida where Melaleuca quinquenervia occurs (Pratt et al.
2013). The melaleuca gall midge has spread from the initial
release sites at an average of 6.0 km/year (Pratt et al. 2013).
Description and Identification
The three larval instars of the melaleuca gall midge feed,
grow, and molt within prominent galls formed on young
shoots of Melaleuca spp. (Gagné et al. 2009). The larvae
of this midge are cylindrical, spindleform, and very small
(Gagné et al. 2009). Larvae range in total length from
0.3–0.5 mm (first instar), 0.6–0.9 mm (second instar), and
Figure 1. Lophodiplosis trifida Gagné adult resting on
vegetation. A) Red dots visible on the plant are eggs. B) Adult resting
Credits: Matthew Purcell, USDA and CSIRO
Melaleuca Gall Midge (suggested common name) Gagné (Insecta: Diptera: Cecidomyiidae: ...Lophodiplosis trifida
1.3–2.0 mm (third instar) (Gagné et al. 2009). Melaleuca
gall midge larvae can be distinguished from the other
species of Lophodiplosis by the absence of setae (hairs)
on most of the papillae (small body protuberances) and a
unique three-toothed spatula on the prothorax of the third
instar (Gagné et al. 2009) (Figure 4).
Melaleuca gall midges pupate within their galls (Gagné
1997; Gagné et al. 2009). The pupae of Lophodiplosis species
have specialized projections on the vertex of the head,
evidently used to cut through plant gall tissue when the
adults emerge (Gagné et al. 2009). The pupal vertex projec-
tion of the melaleuca gall midge is angled along its length
and has three points at its apex (Gagné 1997).
Melaleuca gall midge adults are very small, 2.0–2.3 mm in
length (Gagné 1997) (Figure 5). The females are slightly
larger than males and have red or orange abdomens (filled
with eggs) (Goolsby et al. 2002). Males have thinner
abdomens that end in two distinctive hook-like cerci
(Gagné 1997; Goolsby et al. 2002). Adult melaleuca gall
midges can be distinguished from the other species in the
genus Lophodiplosis by features of the male and female
terminal abdominal segment (Gagné 1997).
Figure 2. Distribution of Lophodiplosis trifida Gagné in Queensland and
New South Wales, Australia.
Credits: Matthew R. Moore, University of Florida
Figure 3. Initial 2008 field release sites for Lophodiplosis trifida Gagné
in Florida. Lophodiplosis trifida Gagné has since established in Florida
and is spreading to areas where its host melaleuca occurs. Locality
data were taken from Pratt et al. (2013).
Credits: Matthew R. Moore, University of Florida
Figure 4. Third instar larva of Lophodiplosis trifida Gagné. A)
Dorsolateral view of entire larva. B) Anterior segments of the larva,
detailing the head, thorax, and spatula. C) First thoracic segment with
lateral papillae (lp) and three-toothed spatula (arrow).
Credits: Recreated from figures 5, 6, and 7 in Gagné et al. (2009)
The melaleuca gall midge was originally thought to live
as an inquiline (i.e., present in the galls of other Lopho-
diplosis species) (Gagné 1997). Subsequent observations
revealed that melaleuca gall midge forms galls on new
stems of Melaleuca quinquenervia following flowering
(Purcell et al. 2007). Persistent galls formed by melaleuca
gall midges on Melaleuca quinquenervia result in damaged
and deformed branches, plant dieback, blockage of vascular
tissues, and sometimes plant death (Goolsby et al. 2002;
Purcell et al. 2007) (Figure 6).
Melaleuca gall midge adults live only one to five days
(Goolsby et al. 2002; USDA 2008). Females can lay
hundreds of eggs on young leaves and stems during their
short lives, with the average female laying 162 eggs under
greenhouse conditions (Goolsby et al. 2002; USDA 2008).
Eggs typically hatch after six days (USDA 2008).
Larvae hatch and burrow into plant stems where their
salivary enzymes initiate gall formation in their Mela-
leuca hosts (Goolsby et al. 2002; USDA 2008). The galling
is much more intense on lower branches of the tree (0–2 m
high, > 75% of available branches are galled) and rates of
galling decrease higher up the tree (Pratt et al. 2014). Galls
formed by melaleuca gall midges can be monothalamous
(having one chamber) or polythalamous (having multiple
chambers) (USDA 2008). It takes about six weeks from
the time that the larva emerges from the egg until the
midge becomes an adult (Goolsby et al. 2002; USDA 2008)
(Figures 7 and 8).
The host range of Lophodiplosis trifida is narrow
(Goolsby et al. 2002; Wineriter Wright and Center 2008).
Experiments demonstrated that melaleuca gall midges
will oviposit on several Melaleuca species and at least one
related Myrtaceae genus (Callistemon) (Goolsby et al. 2002;
USDA 2008; Wineriter Wright and Center 2008). However,
melaleuca gall midges complete their development only
on Melaleuca quinquenervia and two other closely
related Melaleuca species (Goolsby et al. 2002; USDA 2008;
Wineriter Wright and Center 2008).
Figure 6. Galls of the melaleuca gall midge, Lophodiplosis trifida Gagné,
on melaleuca. A) Galls formed on young stems. B) Plant dieback after
persistent gall damage.
Credits: Paul D. Pratt, USDA
Figure 7. Internal structure of Lophodiplosis trifida Gagné gall on a
Credits: Paul D. Pratt, USDA
Figure 8. Newly emerged adult and pupal exuviae of Lophodiplosis
trifida Gagné on melaleuca.
Credits: Lyle J. Buss, UF/IFAS
Figure 5. A) Top; and B) underside of a melaleuca gall midge,
Lophodiplosis trifida Gagné, adult female.
Credits: Lyle J. Buss, UF/IFAS
Melaleuca is an invasive tree species in Florida wetland
ecosystems, where it has the ability to form dense monocul-
tures and greatly reduce plant species diversity. Melaleuca
quinquenervia is native to Australia, New Guinea, and New
Caledonia and was intentionally introduced into Florida
multiple times dating back to the 1880s through 1959
(Craven and Lepschi 1999; Dray et al. 2006).
Melaleuca quinquenervia was and still is cultivated in
various locations around the world including South
America, Africa, Asia, Oceania, and the West Indies (Dray
et al. 2006). This tree is valued as an ornamental plant due
to its exotic-looking bark and flowers (Dray et al. 2006).
Additionally, its bark and wood are used for packing
material and lumber and the oils present in the leaves are
used medicinally (Dray et al. 2006).
It is difficult to determine when melaleuca expanded into
natural areas in Florida due to the lag time between when
the tree escaped cultivation and became sufficiently dense
to be noticed (Dray et al. 2006). By the 1920s, melaleuca
had naturalized in cypress swamps in southwestern and
southeastern Florida (Nehrling 1933; Small 1933). Surveys
estimated that melaleuca occupies at least 200,000 ha of
wetlands in Florida (Bodle et al. 1994; Laroche 1998).
Management of melaleuca is challenging due to its fire
tolerance and ability to sprout again from stumps that have
been cut (Center et al. 2008). This tree threatens several
habitats in Florida including prairies, cypress swamps, pine
forest, hammock, salt marshes, and mangroves (Dray et al.
2006; USDA 2008).
Introduction of the melaleuca gall midge into Florida was
part of a larger control strategy for the melaleuca trees.
Three different insect biological control agents of melaleuca
have been released into Florida and have established.
leaf feeding weevil, Oxyops vitiosa (Pascoe) (Coleoptera:
, was released in Florida in 1997 (Center
et al. 2000, 2012). The weevil reduces the reproductive
potential of melaleuca by consuming young foliage and
destroying stem tips where flowers and fruits are produced
(Balciunas et al. 1994; Center et al. 2000, 2012).
Boreioglycaspis melaleucae Moore (Hemiptera: Psyllidae)
released into Florida in 2002, was the second insect bio-
feeds on the juices of melaleuca and completes its entire
lifecycle on the plant (Purcell et al. 1997; Center et al. 2012).
In 2008, the third established biological control agent, the
melaleuca gall midge, was released in Florida. Melaleuca
gall midges are unlikely to kill or significantly damage
mature melaleuca trees (USDA 2008). However, melaleuca
gall midge damage can kill melaleuca seedlings and
saplings, divert the tree’s resources from growth and
reproduction, and enhance the effects of other biological,
chemical, and mechanical controls (USDA 2008; Tipping et
al. 2008; Rodgers et al. 2014; Rodgers 2016). The melaleuca
gall midge has maintained an extremely narrow host range
in Florida because it completes development only on Mela-
leuca quinquenervia (Pratt et al. 2013).
A combination of control tactics (intensive monitoring,
mechanical removal of trees, and biological control) has
been successful at removing large monocultures of mela-
leuca and limiting regrowth in some parts of the Florida
Everglades (Figure 9).
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