A very common species in Hong Kong. Very wide distribution across much of Asia.
This species, Hong Kong’s most common Polistes, is an average-sized paper wasp, being in the range of 18 to 24 mm. It is a deep yellow overall, and one distinguishing feature is that the antennae and legs are all yellow also. It has some very fine black patterning on the abdomen and on the thorax.
Polistes olivaceus builds a generally round, flat nest, which is usually suspended from a solid, sheltered surface, or hidden in dense foliage. This is another adaptable species which is not averse to nesting near human habitation; nests are very often found under window ledges or even more unusual locations such as inside cabinets and discarded air-conditioning units. The colony usually attains far larger sizes than most other local Polistes, usually in the range of 60 wasps and sometimes exceeding 100. The colony cycle is very long for a Polistes species; in Hong Kong, nests are usually initiated in April each year and only decline in November or December, with some wasps remaining on the nest till January.
Photo above courtesy of Steen Heilesen
Above: A small nest near the end of its life.
Below: A large nest outside my window. This colony attained a rather impressive size from a tiny queen nest I relocated to this location for easy observation. It would have grown more, had it not been attacked by some Vespa species while I was away in Singapore.
Above: A nest built in a heap of discarded canvas!
Below: A fairly large nest built in an old temple. As can be seen from the photograph, the wasps enter and leave through a small gap between the roof tiles.
This is one of the more defensive Polistes species. While it will tolerate activity near the nest, the workers fiercely attack on provocation; fortunately the attack is frequently aimed solely at the intruder. The sting of this species can be quite painful.
Polistes olivaceus usually catches caterpillars and other small insects from grassy areas or among shrubs. It is one of the less specialized species; unlike other Polistes, I have seen it attack and kill other insects, including grasshoppers and dragonflies! They are a very common sight in Hong Kong throughout the warmer months; around six or seven individuals can often be seen slowly drifting around a small patch of grass the size of half a tennis court.
Polistes olivaceus has been recorded from Singapore. I used to read those records with a little skepticism, thinking that given the large colony size and adaptability of this species, it would be easily found everywhere should it occur in a particular country. In March 2007, however, I found an individual flying around a temple in an area which can be considered part of the downtown business district but is fairly quiet and well vegetated. In June 2007, I saw another two, one around the same area and one nearer to my place. Although one of the most common wasps in Hong Kong, it remains one of the rarest wasps in Singapore. Why is this so? I hope I will be able to solve this problem one day.