Cotton stainer
bugs
Dysdercus decussatus
Family Pyrrhocoridae
updated
Jan 2020
Where
seen? This colourful insect is sometimes seen in numbers
when the Sea hibiscus is fruiting. These colourful bugs feed
on the seeds of the Sea
Hibiscus (Hibiscus tiliaceus). Both adults and nymphs are
often found in groups under the leaves or among the flowers of this
plant. Another related Dysdercus feeds on the Portia
tree (Thespesia populnea); it looks similar but has a black
head.
Features: Body about 1cm long.
The adult has a red or black head with distinctive yellow cross on
black wing cases with red bodies and black legs. The juveniles are
all red, wingless with black legs and a black head. |
An adult Bug.
Pulau Semakau, Dec 08 |
Some adults have a black head.
Pulau Ubin, Jan 11 |
Adult Bugs are often found in large numbers
under Sea hibiscus leaves.
Pasir Ris, Apr 09 |
The bugs tend to form groups, which help them find mates. The small,
pale eggs are laid singly on the food plant or dropped on the ground
near the food plant. They hatch in 5-8 days into wingless nymphs which
lack the cross-markings on their backs (they do not have a larval
stage). Hatchlings gather near their egg shells, then continue to
feed in groups. They moult 5 times (instars) before reaching the mature
stage whereupon they get their wings and characteristic cross-markings.
They got their name because many Dysdercus species transfer
microorganisms that stain the cotton bolls that they prefer to feed
on. Bugs that feed on cotton grow larger and faster. Feeding on the
cotton bolls not only stains them an indelible yellow as plant sap
seeps out of the puncture wound, and microorganisms and fungus grows
at the site. The feeding habit also damages the fibres by cutting
them, and affects the growth of the cotton boll. Some species also
damage other agricultural crops such as peaches. |
Juvenile feeding
on Sea hibiscus seeds.
Pulau Semakau, Dec 08
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Berlayar Creek, Oct 15
Photo shared by Marcus Ng on flickr.
|
Cotton
stainer bugs on Singapore shores |
Other sightings on Singapore shores |
Labrador, Nov 15
Photo shared by Marcus Ng on flickr.
|
A mating pair.
Seringat-Kias, Nov 2019
Photo shared by Marcus Ng on facebook.
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