Aquatic macroinvertebrates of Nee Soon 
87 
that the mandibles are a secondary sexual characteristic, meant to attract mates or drive 
off rivals (Cover & Resh, 2008). In contrast, the larvae are voracious predators, and 
feed on almost anything they can catch (Romoser & Stoffolano, 1994; Cover & Resh, 
2008). Megalopterans are rare in the Nee Soon freshwater swamp forest (Fig. 7). Only 
one Corydalidae specimen was collected from site 22 and low numbers of Sialidae (1 
to 2 individuals) were recorded at five sites (sites 6, 9, 18, 19 and 33) (Table 2). 
Order Odonata 
The order Odonata, better known as the damselflies (Zygoptera) and dragonflies 
(Anisoptera), are among the best known groups of insects, due to the visibility and 
bright colours of the adults. Most of the information currently available on the Odonata 
of Singapore focuses on their adult stage (Murphy, 1997; Norma-Rashid et al., 2008; 
Tang et al., 2010; Ngiam & Cheong, 2016). However, knowledge of the aquatic larval 
stages is growing, with a recent study by Yeo et al. (in press) enabling the matching of 
adult and larval stages of 59 odonate species found in Singapore. Currently, 10 families 
of Odonata were documented from the Nee Soon freshwater swamp forest. The most 
commonly recorded dragonfly families were Gomphidae (recorded at 26 sites) and 
Corduliidae (recorded at 13 sites), while the most common damselfly family was 
Protoneuridae (recorded at 12 sites) (Table 2). The Odonata appear to be distributed 
throughout the entire Nee Soon drainage, as they were recorded from 32 out of 40 
sites. However, they are most abundant in the northeast of the Nee Soon drainage (Fig. 
8). For instance, at Site 32, 119 specimens were documented. These specimens were 
largely made up of damselfly larvae (94 Protoneuridae individuals, 1 Platystictidae 
individual and 1 Coenagrionidae individual), along with some dragonfly larvae (12 
Corduliidae individuals, 6 Libellulidae individuals and 5 Gomphidae individuals). 
Further information on the Odonata recorded in the Nee Soon freshwater swamp 
forest is given by Cai et al. (2018). 
Order Plecoptera 
Two families of Plecoptera have been recorded from the Nee Soon freshwater swamp 
forest. This group is commonly known as the stoneflies, and is commonly used as 
an indicator group, since the aquatic nymphs are generally intolerant of pollution 
(Blakely et al., 2014). Some species are herbivorous, while others are predatory 
(Romoser & Stoffolano, 1994). In the Nee Soon drainage, they are relatively rare, 
with one Leutridae individual recorded at sites 4 and 11, and low numbers of Perlidae 
(one to three individuals) recorded at seven sites (sites 1, 4, 5, 15, 24, 34, 40) (Table 
2). Unlike other aquatic invertebrates, Plecoptera were absent in the northeast of the 
Nee Soon drainage (Fig. 9). 
Order Trichoptera 
The order Trichoptera is commonly known as the caddisflies. These insects are well- 
known for the cases which their aquatic larval stages construct, using detritus and silk. 
This group is also commonly used as a bioindicator of aquatic pollution (Yule & Yong, 
2004; Blakely et al., 2014). Eleven families of Trichoptera were found in the Nee Soon 
