1

Colony Structure of the Weaver Ant, Oecophylla smaragdina 
(Fabricius) (Hymenoptera: Formicidae)

by

Marcela, P. ª, Abu Hassan, A.ª, Nurita, A.T.ª & Kumara Thevanb

ABSTRACT
The colony structure of Oecophylla smaragdina within the compound of 

Universiti Sains Malaysia, Penang Island, Malaysia was determined. The current 
study involved a total of twelve nests which were taken from two different 
locations. Each nest was dissected and the specimens were separated accord-
ing to their caste. Results show that the colony structure of O. smaragdina 
consisted of a dealate queen, eggs, larvae of female alates, pupae of major and 
minor workers, pupae of female alates, major workers, minor workers, female 
alates and male alates. Our present study shows that O. smaragdina had a 
distinct caste system and the numbers of individuals in each caste reflect their 
respective functions which contributed to the success of their colony.

Keywords: Oecophylla smaragdina; nests; caste; colony structure

INTRODUCTION

Weaver ants, or Oecophylla, are eusocial insects of the family Formicidae 
(Order: Hymenoptera). They are classified under the subfamily Formicinae. 
Weaver ants are obligate arboreal species and are known for their unique nest 
building behavior where workers construct nests by weaving together leaves 
using larval silk (Hölldobler & Wilson 1990). The Asian weaver ant, O. 
smaragdina is well distributed throughout most of the Oriental region from 
India to Queensland and the Solomon Island (Greenslade 1972). They are also 
common in the lowland of Peninsular Malaysia and have become an important 
ant in the tree canopies of the humid tropics of Southeast Malaysia, Australia, 
and Pacific islands ( Jander & Jander 1979; Bluthgen & Fiedler 2002). 

Previous studies reported the existence of single or multiple queens in 
the colonies of O. smaragdina (Greenslade 1971; Peeters & Andersen 1989; 

ªSchool of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia.
bDepartment of Forensic Medicine, Penang Hospital, 10990 Residensi Road, Penang, Malaysia.
Corresponding author email: aahassan@usm.my



2  Sociobiolog y Vol. 59,  No. 1, 2012

Hölldobler & Wilson 1983; 1990). However, little was known about the 
colony composition and caste system such as the existence of reproductive 
individuals and non-reproductive individuals of these weaver ants. Despite 
being well-studied for other biological attributes, the colony structure of O. 
smaragdina has received less attention (Schlüns et al. 2009). Studies on colony 
structure and caste composition might be able to explain how the social 
structure inside the nest influence the behaviour of individuals outside the 
nest. Therefore, the objective of the current study was to report the colony 
structure of O. smaragdina inside the nests of this species.

MATERIALS AND METHODS

This study was conducted in November 2010 until February 2011 at the 
main campus of Universiti Sains Malaysia, Penang Island, Malaysia. Two 
colonies of weaver ants, located 500 m from each other, were chosen for this 
study. The boundary of each colony was determined by following the ant 
trails. The first colony was located behind the “Kelas Al-Quran dan Fardu 
Ain” building (KAFA) and the second colony was located near the building 
of the School of Industrial Technolog y (TI). The KAFA colony made nests 
on five mango trees (Mangifera indica) whereas the TI colony made nests in 
a “mempari” tree (Millettia pinnata). Total nests sampled were twelve, where 
eight nests taken from the KAFA colony and four nests from the TI colony. 
These nests were removed from the trees by cutting the base of the nest using 
a long cutter (Sharpex) and placing it into plastic buckets (60 cm x 80 cm) 
containing cotton wads wetted with chloroform. 

All nests were collected in between 10 a.m. to 12 p.m., corresponding to the 
time of day when the weaver ants were least active which was determined in a 
preliminary study. Each nest was kept separately in individual plastic buckets. 
These plastic buckets were brought back to the laboratory and kept inside a 
fume hood for 24 hours to ensure that the weaver ants were all dead. After 24 
hours, the nests of O. smaragdina ants were dissected and sorted according 
to the following castes: dealate queens, egg, larvae, pupae, female alates, male 
alates, major workers and minor workers. The number of individuals of each 
caste for each nest were counted and recorded. The collected specimens were 
preserved in 95 % ethanol. The images of each specimen of O. smaragdina were 



3 Marcela, P. et al. — Colony Structure of Oecophylla smaragdina 

captured and s measurements were deter-
mined using a stereomicroscope (Olympus 
SZX9) which was connected to Image 
analyser Cell A (Dell Inc. computer). The 
mean number and standard error of mean 
(S.E.M) for each caste was determined using 
Statistical Packages for the Social Sciences 
(SPSS 11.5). 

RESULTS

Table 1 shows the caste composition 
of O. smaragdina from the twelve nests 
sampled. One dealate queen was found 
in the KAFA colony (Fig. 1). The dealate 
queen of O. smaragdina found in the field 
was green to brown in color. In contrast, 
the male alates of O. smaragdina were black 
in color and smaller in size (Fig. 2). The 
female alates of the KAFA colony were 
green in color with unshed wings (Fig. 3). 
However, the female alates of the TI colony 
were yellow in color with unshed wings (Fig. 
4). The major workers were bigger in size 
compared to minor workers (Fig. 5; Fig. 6). 
Table 1 also shows that the highest number 
in any individual caste was male alates in 
the KAFA colony (1384.38 ± 367.57), 
however no male alates were observed in 
the TI colony. In addition, the number of 
major workers was higher than the minor 
workers for both colonies (KAFA= 553.38 
± 123.82; 441.88 ± 79.23) (TI= 390.00 
± 51.15; 193.25 ± 19.64). Both eggs and 
larvae were white in color and similar in 

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4  Sociobiolog y Vol. 59,  No. 1, 2012

1     2

     4

3    ``  4 

5     
     
5     6

Figs. 1-6: Fig. 1. Dealate queen of O. smaragdina from KAFA colony; Fig. 2. Male alate of O. smaragdina 
from KAFA colony; Fig. 3. Female alate of O. smaragdina from KAFA colony; Fig. 4. Female alate 
of O. smaragdina from TI colony; Fig. 5. Major worker of O. smaragdina from both colonies; Fig. 6. 
Minor worker of O. smaragdina from both colonies.

shape but the larvae were bigger in size (Fig. 7; Fig. 8; Fig. 9). The pupae had 
developed eyes, mouth, legs and wings that were very similar to the adults 
(Fig. 10; Fig. 11; Fig. 12).



5 Marcela, P. et al. — Colony Structure of Oecophylla smaragdina 

DISCUSSION

The current study showed the basic colony structure of O. smaragdina ants 
consisted of dealate queens, male alates, female alates, major workers, minor 
workers, eggs, larvae and pupae. This result corresponded to Lee et al. (2003) 

Figs. 7-12: Fig. 7. Eggs of minor worker of O. smaragdina from both colonies; Fig. 8. Eggs of major 
worker of O. smaragdina from both colonies; Fig. 9. Larvae of female alate of O. smaragdina from 
both colonies; Fig. 10. Pupae of minor workers of O. smaragdina from both colonies; Fig. 11. Pupae 
of major workers of O. smaragdina from both colonies; Fig. 12. Pupae of female alate of O. smaragdina 
from both colonies.



6  Sociobiolog y Vol. 59,  No. 1, 2012

where the O. smaragdina ants had a complete metamorphosis consisting of 
immature stages (eggs, larvae, and pupae) and adults with reproductive stage 
(dealate queen) and non-reproductive stage (workers). The workers of O. 
smaragdina were all females and had a dimorphism or bimodal size-frequency 
distribution known as major and minor workers (Wilson 1953; Greenslade 
1972; Hölldobler & Wilson 1990).The specific function of each individual 
adult in a colony is determined by the existence of the caste system and this 
division of labour is important for the continuous survival of the colony 
(Lee et al. 2003). Contrary to the current study, Peng et al. (1998a; 1998b) 
reported that there were large numbers of major workers, eggs, early-instar 
larvae and some minor workers within each queen nest, but no pupae or 
medium-sized or large-sized larvae. Way (1963) also reported that the brood 
(immature stages) of O. smaragdina is not raised in ‘pavilions’; the pavilions 
are constructed in the same way as nests where many homopterans are tended 
by ants, often several meters away from the nearest ant nest. 

Only one dealate queen found in the KAFA colony and no dealate queen 
was found in the TI colony. This may be due to the KAFA colony was estab-
lished much earlier than the TI colony. The nests which were taken from the 
TI colony were also fewer in numbers and smaller in size compared to the 
nests of the KAFA colony. Similar to the present study, Peng et al. (1998b) 
reported that young mango trees which were closer to the matured mango 
trees with well-established O. smaragdina colonies were found to have more 
dealate queen nests. After being inseminated by a male ant during nuptial 
flight, the winged queen shed her wing (Oster & Wilson 1978; Lokkers 
1990). The queen would then begin to construct the first nest cell and rears 
its first brood of workers. Soon, the workers would take over the tasks of 
foraging and brood care, allowing the queen to confine herself to egg-laying 
(Oster and Wilson 1978). Therefore, the presence of a dealate queen in the 
KAFA colony showed that the colony was well-maintained compared to the 
TI colony. 

The number of male alates in the KAFA colony was higher than the fe-
male alates might be due to the female alates could mate with more than one 
male during swarming (1384.38 ± 367.57; 80.00 ± 26.09). This result was 
supported by Schlüns et al. (2009) who reported that direct genotyping of 
the sperm carried by 77 Queensland queens and worker genotypic arrays of 



7 Marcela, P. et al. — Colony Structure of Oecophylla smaragdina 

established colonies of O. smaragdina showed that less than half of the queens 
mate only once, while some mate up to five times, which suggested that more 
males were involved during mating than the females. Similar behavior was also 
observed in Formica subpolita ants where the females controlled who they 
mated with and were observed to mate with up to 4 different males, before 
dispersing from swarm sites (O’Neill 1994). Female ants may mate just once, 
but multiple mating is apparently typical for many species (Hölldobler & 
Wilson 1990). Lee et al. (2003) explained that male ants have only one task, 
which is to inseminate the queen. They usually possess wings and mating can 
occur within the nest or outside the nest (swarming ). Shortly after mating, 
the males die and the queens settle and establish new colonies (Schlüns et al. 
2009; Lee et al. 2003).

For the female alates found inside the nests, the yellow color was also ob-
served in the study of intercolony transplantation of O. smaragdina by Krag 
et al. (2010). They reported that the O. smaragdina can be categorized into 
the following distinct groups: larvae, pupae, light yellow callow workers and 
red mature workers. Lee et al. (2003) explained that a newly hatched adult 
which has not yet acquired its deep coloration is known as a callow. It will 
undergo coloration as it grows older. Therefore, it could be that the yellow 
colored female alates of the TI colony were newly emerged adults that had 
not yet acquired its deep coloration (callow) (Fig. 4). This result supported 
that the KAFA colony was established much earlier than the TI colony due 
to the presence of the matured female alates with greenish color in the KAFA 
colony. Our results also show that the number of female alates in the KAFA 
colony was higher than the TI colony (80.00 ± 26.09; 11.00 ± 5.08). 

The higher number of major workers compared to minor workers discovered 
in the current study could be due to task allocation. The major workers have 
more tasks than the minor workers do and therefore more major workers would 
be needed (Lee et al. 2003). This result corresponds to previous studies which 
demonstrated that the major workers do virtually all of the foraging, defend 
the colony, care for the queen and assist in the care of the brood (Chapuisat 
and Keller, 2002), whereas the minor workers mostly remain inside the leaf 
nests and function as nurses of the brood studies (Hölldobler & Wilson 1978; 
1990). This allocation of tasks to different castes of O. smaragdina creates an 
efficient society (Saarinen 2006).



8  Sociobiolog y Vol. 59,  No. 1, 2012

The eggs were small and ellipse-shaped with a size around 0.5 mm x 1.0 mm. 
The eyes and mouth of the larvae within the eggs could be seen when they 
were observed under a magnifying glass. The pupae could be differentiated 
from the mature adults because they were white in color (Van Mele & Cuc 
2007). The O. smaragdina colonies could produce a large number of “queen 
brood” every year. The “queen brood” refers to larvae and pupae, which are 
destined to become new queens as well as their last stage as imago virgin 
queens (Cesard 2004; Offenberg & Wiwatwitaya 2010). The current study 
also showed that O. smaragdina ants built new nests within 14 days after their 
nests were taken. The new nests were located near to the nests which were 
taken for our study. Regarding this condition, Paimin and Paimin (2001) 
reported that under normal conditions, weaver ants have a quick population 
recovery with regeneration time between 17 and 24 days. Others reported 
it takes five days before new nests appear and around 20 days for the ants to 
produce new larvae (Cesard 2004). 

A caste can be characterized as a set of individuals in a colony, morpho-
logically distinct from other individuals and specialized in behavior which 
performs specialized task in the colony (Oster & Wilson 1978). The present 
study showed that different caste of O. smaragdina ants performed different 
but specific task to maintain their colony well. Hölldobler & Wilson (1990) 
stated a colony which is large enough to produce new, virgin queens known 
as “mature colony” and the efficiency of the mature colony is determined by 
the number of workers in each temporal caste at any given moment. This 
suggests that the KAFA colony in the current study was a mature colony 
of O. smaragdina with the presence of a dealate queen and more workers 
compared to the TI colony.

ACKNOWLEDGMENTS

The authors thank the Dean of the School of Biological Sciences, Universiti 
Sains Malaysia for the facilities and funding provided for the research.

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