Citrus Peel Miner Marmara salictella Monitoring Techniques and Control Measures 1996-97
M.A. Maurer, Associate Research Scientist, Plant Pathology, Yuma Agricultural Center
D.L. Kerns, Assistant Specialist, Entomology, Yuma Agricultural Center
T. Tellez, Research Specialist, Yuma Agricultural Center
Citrus peel miner populations were monitored to evaluate various methods of trapping citrus peel
miners. Observing 25 fruit per tree and 10 trees per block on the lower three feet of the tree canopy
provided the best technique for determining the level of citrus peel miner infestations. The use of
oleander plants, clear plates and green 3 inch diameter balls sprayed with Tangle-Trap were not effective
in trapping citrus peel miner. In 1996, the first of September citrus leaf miner populations rose above
the 10% infestation level. Success, Lorsban, Alert and Agri-Mek provided the highest mortality levels of
citrus peel miner larvae. In citrus fruit, Success, Lorsban and Alert had the greatest efficacy of citrus
peel miner larvae.
The citrus peel miner (Marmara salictella Clemens) is not a new pest problem of desert citrus.
It has been present in Arizona for a number of years. It is typically found at low populations, but in
certain years is an economic pest of citrus. The difficulty has been the sporadic nature of the citrus
peel miner. This has made research and control programs difficult to establish. The citrus peel miner
was first described in 1863 by J.B. Clemens. However, it was not until 1917 that S.C. Vinal reported
citrus peel miners on orange peels in Southern California. Since citrus peel miner problems have been
reported in 1933 (Lockwood, 1933), 1948 (Woglum, 1948), 1955, 1971 (Atkins, 1971), 1984-85 (Reeves, 1995)
and 1993 (Gibson, et. al., 1997).
Citrus peel miner appears to have a extensive host range and in addition to citrus has been found
infesting oleander, willow, grape and cotton. In oleander they are considered an economically damaging
pest where cuttings are used for propagation. Fresh oleander cuttings infested with peel miner will
often become infected with secondary plant pathogens and fail to root properly.
In a laboratory study Atkins (1961) determined the life cycle of the citrus peel miner at 80 F, but
under field conditions during late summer in Arizona, these values maybe reduced. Eggs are deposited
singly on the stem or more preferably citrus peel and hatch in about 5 days. The eggs are very small,
oval in shape and convex on top. They are whitish in color and the top has some indistinct sculpturing.
The number of eggs produced per female moth is not certain, but some have laid 7 to 12 eggs over a 4-day
The larvae exit the egg from the bottom and immediately burrow into epidermal layer of the peel.
Thus they are never exposed. The larvae will extensively mine the peel of the fruit while passing through
6 instars. The 6th instar cuts out of the mine and lowers itself via a silken thread, to
the ground or niche on the tree to pupate. The larvae complete their development cycle in 20-28 days.
The pupa is yellow in color and covers itself with a silken cocoon. The cocoon is silverish-white
and covered with approximately 40 small silverish-white ball shaped objects. The pupal stage lasts 10-14
days, after which the adult emerges. The adults are about the size of a mosquito. Their forewings are
dusky grayish-black with one silvery-white band across the wing about a third from the base of the wing.
More silvery-white mottling can be found towards the tip of the wing. The wings are held length wise over
the body when at rest. The adult will rest in the shade during the day, and beginning dispersing near dusk.
The adults will generally begin laying eggs about 2 days after emerging. Citrus peel miner appear to prefer
ovipositing on larger fruit, i.e. Grapefruit is preferred to navel oranges and navel oranges are preferred
Monitoring is the cornerstone to most pest management programs. Ideally, to would be beneficial to be
able to detect adult peel miner movement into the grove. Thus allowing the grower to time insecticide
applications toward the adults before any damage can occur, and/or to time for maximum egg hatch.
Unfortunately there is no commercially available pheromone to monitor citrus peel miner adults, nor can
they be trapped on yellow sticky cards or with black lights. Field observations have determined that the
greatest fruit damage occurs on the lower 3 feet of the citrus tree canopy (Atkins, 1971 and Gibson et. al.,
1997). In addition, most of the mined fruit appear to be in the internal canopy of the tree. The use of
Guthion and Parathion were reported to be the most effective materials for control of the citrus peel miner
(Atkins, 1971). Trees treated with Guthion on 26 September and 8 October had 15.4 and 37.5% mined fruit,
respectively (Atkins, 1971). Application timing is critical to achieve maximum control of the citrus peel
In this study, we investigated several alternatives for monitoring citrus peel miner adults and larvae.
Additionally, we investigated several insecticides for controlling this pest.
Materials and Methods
To evaluate monitoring techniques two groves (Cactus Lane Ranch) were selected, one was a mature grove
of 'Ruby Red' grapefruit and the other a young grove of 'Rio Red' grapefruit. Both groves had previous
histories of citrus peel miner problems.
We attempted to monitor adult peel miners using three techniques. Since oleander is considered a favorite
host of the peel miner, oleander plants may serve as an indicator of peel miner activity before they are
attracted to the citrus fruit. Oleander plants were obtained from Desert Winds Nursery which were free of
citrus peel miner and placed between citrus trees in the groves.
Since peel miner adults appear to be attracted to larger fruit, we attempted to monitor adult activity
using 3-inch diameter wood balls, which were painted green to match the color of immature grapefruit.
The spheres were then sprayed with Tangle-Trap and placed in the inside of the tree canopy in each of the
4 quadrants of the tree.
A passive monitoring technique was also attempted. In Florida, investigators have been attempting to
monitor the movement of a similar insect species in citrus, the citrus leafminer, Phyllocnistis citrella
Stainton. They found that very high populations of leafminer adults could be passively captured using
clear Plexiglas plates sprayed with Tangle-Trap. We evaluated this technique using 3 X 5-inch plates placed
in the 4 quadrants of the tree.
In addition monitoring for adults, we monitored for larval activity. Twenty-five fruit from the inside
of the lower 3 feet of the tree canopy were randomly selected and evaluated for the presence or absence
of citrus peel miners.
Oleander plants, spheres, plates and citrus fruit were evaluated weekly. Each grove contained of 10
replicates of the four different monitoring techniques.
Timing and insecticide efficacy
Six year old 'Rio Red' grapefruit trees at Cactus Lane Ranch (Maricopa County) were treated with
insecticides for the control of citrus peel miner. The treatments were arranged in a completely randomized
block with 6 replicates. Each replicate consisted of a single tree (20 x 20-ft). Treatments consisted of 5
insecticides (Dipel 2X, Lorsban 4F, Provado 1.6 F, Alert and Admire) and an untreated control and 6
applications sequentially for 6 weeks (16, 23, 30 July, 6, 13 and 20 August). All treatments were applied
with X-77 non-ionic surfactant at 0.1% v/v, except the Admire, which was applied as a soil drench on only
two application dates (16 July and 6 August). Applications were made with a handgun sprayer calibrated to
deliver 200 gpa. Fruit were harvested and percentage of mined fruit determined.
Efficacy of citrus peel miner larvae on oleander
In a preliminary efficacy test, insecticides were evaluated for their efficacy to peel miners infesting
oleander plants. Oleander plants (Nakase Nursery) infested with citrus peel miner larvae were found and the
stems were cut off. The cut end of the oleander stem was then placed in a water-pick and the top was trimmed
to 10 inches. The cut stem was then placed in a collective pile.
Once 120 stems with citrus peel miners were collected, the stems were arranged in a randomized complete
block design for treatment. Each treatment was replicated 4 times with 5 oleander stems per replicate.
Treatments consisted of untreated control, Agri-Mek (abamectin) at 10 oz/ac, Provado (imidacloprid) at 0.1
lbs-ai/ac, Alert (chlorfenapyr) at 0.3 lbs-ai/ac Success (spinosad) at 9.0 oz/ac and Lorsban (chlorpyrifos)
at 3 qt/ac. All treatment except Agri-Mek included the non-ionic spreader Kinetic at 0.1% v/v.
Agri-Mek included NR-415 spray oil at 1 gal/ac. Applications were made using a backpack air-blast sprayer
calibrated to deliver 100 gpa. After treatment stems were allowed to air dry, they were placed in paper bags
and transported to the lab. In the lab stems were placed in 3 gal buckets (1 bucket per plot) with
ventilated lids. After 21 days, the numbers of emerged adult citrus peel miners were counted.
Henderson - Tilton's equation [C = 100(1 - XcYt/YtY,c);
where C = percent control, Xc = precount untreated,
Xt = precount in the treatment, Yc = post count in the untreated and Yt = post count in
the treatment] was
used to estimate percent control. Differences among treatments were separated using ANOVA and F protected
Efficacy of citrus peel miner larvae on grapefruit
Ten year old 'Rio Red' grapefruit trees in Maricopa County, AZ (Gila River Farms) were treated with
insecticides to control citrus leaf miner larvae. The treatments were arranged in a randomized complete
block design with four replicates. Each plot (20 x 60 ft) consisting of three trees in a row 20 ft apart.
Applications were initiated as soon as visible mines were detected. Applications were made using a backpack
air-blast sprayer calibrated to deliver 100 gpa. Prior to application, 10 to 15 fruit with active mines
were tagged in each plot. Treatments included Agri-Mek (abamectin) at 10 oz/ac, Provado (imidacloprid) at
0.1 lbs-ai/ac, Alert (chlorfenapyr) at 0.3 lbs-ai/ac Success (spinosad) at 9.0 oz/ac, Dimethoate 267
(dimethoate) at 2 qt/ac and Lorsban (chlorpyrifos) at 3 qt/ac. All treatment except Agri-Mek included
the non-ionic spreader Kinetic at 0.1% v/v. Agri-Mek included NR-415 spray oil at 1 gal/ac. Treatments
were applied on 18 September. The following day, the fruits were picked and the numbers of mines on each
fruit were counted. They were than placed in 3 gal buckets with ventilated lids, and transported to the
laboratory for storage. The numbers of emerged adult citrus peel miners were counted on 11 October.
Statistical analysis was used as previously described. Fruit were harvested and percentage of mined fruit
determined. Henderson - Tilton's equation [C = 100(1 - XcYt / YtYc);
where C = percent control, Xc = precount untreated, Xt = precount in the treatment,
Yc = post count in the untreated and Yt = post count in the treatment] was used to
estimate percent control. Differences among treatments were separated using ANOVA and F protected LSD.
Results and Discussion
The use of oleander plants for monitoring citrus peel miners was ineffective as citrus peel miner larvae
were detected in citrus fruit prior to detection in oleander plants. Although, the citrus peel miner is
known to infest oleander plants (Gibson et al., 1997) in the grove oleander plants were not a preferred host
of the citrus peel miner. Citrus peel miners infested the oleander concurrently with the citrus fruit.
The use of sticky plates and spheres were likewise ineffective as monitoring techniques as no citrus peel
minor were found on any of the traps. The only effective means of monitoring the citrus peel miner was
by randomly selecting 25 fruit per tree from the lower 3 ft of canopy focusing on the inside of the canopy.
Citrus peel miner populations began to increase by the middle of August 1996 (Fig. 1 and 2), which is
similar to the findings of Gibson et al. 1997.
The best monitoring techniques is looking for citrus peel miner mines in the fruit itself.
It appears that by randomly selecting 25 fruit from the inner, lower 3 ft of tree canopy is the best
way to determine citrus peel miner levels. A minimum of 10 trees should be selected for monitoring,
concentrating on areas in the grove known to previously have citrus peel miner problems. Previous
observations in a 40-acre block of grapefruit indicate that citrus peel miner populations seem to be
ubiquitous throughout the grove (Maurer, unpublished data).
Timing and insecticide efficacy
There was no significant difference in any of the treatments in this experiment. The percentage of
mined fruit averaged 5.5, 4.6, 7.4, 5.0, 5.0 and 5.1 for all the Dipel, Alert, Provado, Lorsban, Admire
and the untreated control treatments, respectively. The low level of citrus peel miner in this grove was
likely the reason no differences between treatments was observed. The previous year (1995), this same
grove averaged 25 to 30% mined fruit (Maurer, unpublished data). It appears that parasites or the sporadic
nature of the citrus peel miner have resulted in populations which were not of economic significance in 1997.
Efficacy of citrus peel miner larvae on oleander
Agri-Mek, Alert, Success and Lorsban had significantly higher mortality rates of citrus peel miner larvae
than Provado (Table 1). Although, the Agri-Mek was not significantly different from Alert, Success and
Lorsban the percent mortality was 80%, which was lower than the other compounds. The result of this
experiment indicate that pesticides are available for the control of citrus peel miner larvae.
Efficacy of citrus peel miner larvae on grapefruit.
Alert, Success and Lorsban provided the best control with over 95% mortality of citrus peel miner larvae
(Table 2). Agri-Mek provided moderate control, while Provado and
Dimethoate provided the poorest mortality (Table 2).
The percentage of mined fruit at harvest was not significantly different for any of the
treatments (Table 2). This may be attributed to the fact that most of the fruit had been mined prior to
treatment when live citrus peel miner larvae were sprayed. Although, the controls average 29.1% mined
fruit in 1996 the level of mined fruit in this grove averaged less than 5% in 1997.
In conclusion, we were unable to detect a reliable technique for monitoring citrus peel miner adults.
Thus sampling for larvae is the only effective monitoring tool currently available. Under normal
circumstances, the peel miner is kept in check by parasitic wasps. We know that citrus peel miners
commonly infest cotton. It is our belief that in 1994-95, numerous insecticide applications targeting
whiteflies in cotton, destroyed the citrus peel miner's parasitoid complex. Thus, citrus peel miners were
able to build-up high densities in the cotton, and move to citrus in August with few parasitoids to follow.
Thus, growers and pest control advisors should start by sampling oleander and cotton, (particularly if its
not BT-cotton) in July and early-August. If heavy mining is detected, nearby groves should be watched
closely. In citrus, sample primarily from the middle and lower portions of the tree canopy beginning in
late July and continuing through November, or until temperatures begin to cool considerably. Treatments
should be applied as soon as 5-10% of fruit is infested with ½ inch or less long mines. Lorsban and
Success have both been shown to be effective towards citrus peel miner larvae, however Lorsban should be
avoided because of its harshness towards parasitoids and other beneficial insects.
Since 1995, citrus peel miner has been a significant pest in Maricopa County. Again, this probably
relates to the insecticide use patterns in cotton. Beginning in 1996, cotton growers received Section
18's registrations for Applaud and Knack for control of whiteflies in cotton. These products are highly
specific to whiteflies and probably had little impact on the citrus peel miner or its parasitoids. Thus,
restoring ecological balance to the citrus peel miner / parasitoid ecosystem. If heavy insecticide use
once again occurs in Arizona cotton, citrus growers should pay close attention to the citrus peel miner
populations. Another factor that may influence the abundance of citrus peel miners is the amount of cotton
acreage planted to BT-cotton. Since peel miners are Lepidopterous pests, they may be susceptible to B.T.,
and may not be able to develop in BT-cotton. However, this relationship has not yet been determined.
- Atkins, E.L. Jr. 1961 Citrus peel miner. In The California Citrograph, September 46(11):367-371.
- Atkins, E.L. Jr. 1971. Citrus peel miner, more problems in the desert. In The California Citrograph, June 56(8):245-246, 267.
- Clemens, J. B. 1863. North American microlepidoptera. Proc. Ent. Soc. Phil. 2:6-8.
- Gibson, R., D. Bacon, D. Langston, D. Kerns and R. Gibson. 1997. 1997 Citrus Research Report. The University of Arizona, Cooperative Extension, Agricultural Experiment Station, College of Agriculture Series P-109:1-6.
- Lockwood, S. 1933. Orange peel miner. Calif. Agr. Monthly Bul. 22:343.
- Reeves, E.L. 1995. Citrus peel miner problems. CPPDR. January - May p. 14-16.
- Vinal, S.C. 1917. Notes on the life-history of Marmara elotella Busck, A lepidopterous sap feeder in apple twigs. Jour. Econ. Ent. 10(5):488-496.
- Woglum, R.S. 1948. A willow pest that occasionally injures oranges. Calif. Fruit Growers Exchange, Pest control Circular No. 168, P. 658.
The authors wish to thank the Arizona Citrus Research Council for supporting this project.
This is the final report for project 97-01 'Citrus peel miner Marmara salictella monitoring
techniques and control measures'.