Identifying and Managing Melon Insects
» Insects and mites can significantly reduce yield potential and melon quality.
» Appropriate control strategies are based on accurate identification of the pest.
» A combination of cultural and chemical management methods are available for most insect pests of melons.
The greenhouse whitefly and the silverleaf whitefly are both
economically important for melon production.1 Both species
are small (<16th of an inch long) flies with powdery white
wings.2 The greenhouse whitefly is found mostly in
greenhouses and other protected environments in
temperate regions, while the silverleaf whitefly is found
mostly in tropical and subtropical areas, as well as in
greenhouses.3 At rest, the silverleaf whitefly holds its wings
vertically tilted (roof-like) and the wings do not meet over the
back (Figure 1). Greenhouse whiteflies hold wings flatter, and
there is no space where wings meet over the back.1 The adults
and nymphs reside mostly on the undersides of leaves.
Affected plants are stunted and have low productivity.
Whiteflies produce a thick, sugary secretion called honeydew,
which can make the leaves and fruit sticky and promote the
growth of dark-colored sooty mold fungi. Fruit covered with
sooty mold growth are unmarketable.1,2,3 Whiteflies also
vector some important melon viruses.
Make sure that transplants are not infested before planting,
and avoid planting near older fields of host crops (cole
crops, cotton, cucurbits, or tomatoes). Reflective mulches
can help repel whiteflies early in the season. Row covers can
be used as physical barriers, but they must be removed
prior to flowering.2,3 Monitor whiteflies by using yellow sticky
traps or by examining the undersides of young, fully
expanded leaves early in the morning. If adults are found on
more than 50% of the leaves, insecticide treatments may be
needed. However, broad-spectrum insecticides can harm
natural enemies of whiteflies, resulting in increased whitefly
numbers. Insecticidal soaps and oils, such as Organic JMS
Stylet-Oil®, can also help manage whiteflies.1,2,3 Using
insecticides to control whiteflies is usually not effective for
preventing transmission of the viruses they vector because
the viruses move into the plants before there is time for the
insecticides kill the whiteflies.
Melon aphids have soft, ovoid bodies that vary in color from
pale yellow to green to black and are up to 1/16th of an inch
in length.2,4 They have black cornicles (posterior tailpipes),
eyes, and leg joints, and occur in winged and non-winged
forms.2,5 Aphids usually start to colonize the undersides of
melon leaves when plants start to form runners.1,4 Heavy
feeding can result in young leaves becoming distorted,
thickened, and curled. Aphids also produce honeydew,
which makes leaves and fruit sticky and promotes the
growth of dark sooty mold fungi.1,2,4 Melon aphids can also
vector several important melon viruses.
Melon aphids are normally controlled by natural enemies,
but outbreaks can result from insecticide applications that
reduce the populations of beneficial insects.4 If possible,
delay planting in the spring until temperatures reach 80°F
and spring aphid flights are completed. Preserve habitats of
beneficial insects and avoid planting melons near cotton and
other host crops.1,2 Reflective mulches can help repel aphids
when plants are small, and row covers can be used to
prevent colonization prior to flowering. Soil applications of
neonicotinoid insecticides have been effective at controlling
aphids on melons. With localized infestations, colonized
plants can be spot treated with insecticides or removed and
destroyed.1,2,3 Rosemary oil, neem oil, and insecticidal soaps
can help manage aphids in organic production systems.3,6
Using insecticides to control aphids is usually not effective
for preventing the transmission of aphid vectored viruses.
Cucumber beetles (striped, spotted, and banded) can feed
on melon plants, causing damage and transmitting the
bacterial wilt pathogen. Striped cucumber beetles are most
problematic east of the Rocky Mountains, while Western
striped cucumber beetles occur west of the Rockies.3
Striped beetle adults are 1/5- to 1/4- inch-long and have
yellow wing covers with black longitudinal stripes (Figure 2).
The head and abdomen are black. Western striped beetles
are about 1/3-inch long and have yellow to greenish wing
covers with alternating black and yellow stripes.2,4,5 Both the
striped and western striped beetles can overwinter in
northern areas. Spotted cucumber beetle adults have
yellowish-green wing covers with 12 black spots, black head
and thorax and yellow abdomen. These beetles overwinter in
southern areas and migrate northward during the season. Adult
banded cucumber beetles are yellowish-green with three bright
green bands running across the wing covers. These beetles are
found mostly in southern growing regions.1,4 Larvae feed on
roots and can kill young seedlings. Adults prefer to feed on leaves
and flowers, but they can feed on fruit, causing damage to fruit
surfaces, especially on smooth-skinned melons (honeydew,
Row covers can be used to keep cucumber beetles from
feeding on young plants, but the covers need to be removed
before flowering.3 Cucumber beetle control often relies on
the application of insecticides once beetle populations have
reached the action threshold. Scouting for cucumber
beetles should begin shortly after planting. Scout twice a
week early in the season, examining the undersides of
cotyledons and young leaves. Treatment may be needed
when counts reach one beetle per plant in the seedling
stages. Older plants can tolerate higher populations.1,5
Insecticide sprays should be directed at adult beetles, which
are most active at dawn and dusk.1,5 Neonicotinoid
insecticides applied in-furrow or to transplants at planting
can help protect young seedlings.3 Foliar applications of
approved insecticides may be needed to protect plants
during the season until harvest.6
Darkling beetles can also cause damage on netted melons.
These beetles are black to brown to gray in color and 1/8- to
1/4-inch long. Females lay eggs in the soil, and both larvae
and adults feed on the fruit where the fruit is resting on the
soil, causing “ground spot”. Cavities develop in the fruit,
making them unmarketable. These beetles are difficult to
control with insecticides once they are under the fruit.
Insecticide treatments when the beetles are moving into the
field can reduce damage. In the southwestern desert
regions, insecticide applications should start when fruit net
development begins and continue through harvest.3
Adult seedcorn maggots are gray-brown in color and about
the size of a small housefly. The larvae (maggots) are pale
yellowish-white and up to 1/4-inch long.2 Adults are active in
the early spring and lay eggs in cool, wet soils, especially in
soils with high levels of organic matter.2,5 Maggots bore into
seed and stems of seedlings, destroying the seed and often
killing seedlings. Management strategies include planting or
transplanting on well-drained soils when soil temperatures
are above 70°F at a 4-inch depth. Wait at least two to four
weeks after incorporating a cover crops before planting, and
avoid planting melons after root- or cole-crops.1,2,5
Several species of spider mites can occur on melons, with
the two spotted spider mite being the most common.1
These insect-like creatures have eight legs on small
(1/50th-inch long) oval bodies (Figure 3). They are found
mostly on the undersides of leaves where they can produce
spider-like webbing. They cause chlorosis and small specks
(stippling) on leaves. Eventually, leaves can shrivel and die,
exposing fruit and causing sunburn. They often proliferate
during hot, dry conditions.1,3,4
Spider mites are normally controlled by natural enemies,
and outbreaks can occur following insecticide applications
that harm beneficial insects.4,6 Avoid excessive nitrogen
fertilization and water stress.3 Insecticidal soaps and neem
oil can help reduce spider mite damage. However, applying
soaps in direct sun or to drought-stressed plants may result
in plant damage.4 Miticides, such as Agri-Mek®SC Miticide/
Insecticide, and Acramite®-50WS Miticide, can be used if
1 Natwick, E., Stapleton, J., Stoddard, C. 2012. Cucurbits. UC Pest Management Guidelines. UC IPM.
2 Webb, S. 2017. Insect management for cucurbits (cucumber, squash, cantaloupe, and watermelon). University of Florida IFAS Extension. ENY-460.
3 Keinath, A., Wintermantel, W., and Zitter, T. 2017. Compendium of cucurbit diseases and Pests. American Phytopathological Society. St. Paul, MN.
4 Williamson, J. and Griffin, R. 2016. Cucumber, squash, melon & other cucurbit insect pests. Clemson Cooperative Extension. HGIC 2207.
5 Reiners, S., Bellinder, R., Curtis, P., Helms, M., Landers, A., McGrath, M., Nault, B., and Seaman, A. 2017. Cornell integrated crop and pest management guidelines for commercial vegetable production.
6 Foster, R. 2008. Insects of melons. Purdue University.
For additional agronomic information, please contact your local seed representative. Developed in partnership with Technology, Development & Agronomy by Monsanto.
Individual results may vary, and performance may vary from location to location and from year to year. The information provided in this communication may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. The recommendations in this article are based upon information obtained from the cited sources and should be used as a quick reference for information about melon insect pests. The content of this article should not be substituted for the professional opinion of a producer, grower, agronomist, pathologist and similar professional dealing with this specific crop. SEMINIS DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE. 170826152019 120117DME
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