Sunday, 9 January 2011
Bristol Mantids 1: Not exactly a Stradivarius
Like other insects, they are most numerous and diverse in rainforests, but some can tolerate colder conditions, although there are none native to the UK. Some have been introduced outside their natural range – the European mantis, Mantis religiosa, has been introduced to North America and ranges as far north as Quebec and British Columbia.
Mantids, like most invertebrate predators, are ambush hunters, relying on superb camouflage to conceal themselves from their prey. They are divided into several families, and we have representative species from several here at Bristol. I will start this series with one of the odder appearing species, the Indian Violin Mantis Gongylus gongyloides.
The first thing anyone learns about mantids is that during mating the female eats her mate. As with most things everyone knows, this is not entirely true – the story arose from observations of captive specimens and in the wild, while cannibalism during mating does occur, it is much less common and in some species does not appear to occur at all. The Violin mantis is one of these – in fact they can be kept in groups, and we have 6 on show together (admittedly in a fairly large enclosure considering their size).
Originating from India and with a range east to Thailand, Violin mantids are decidedly heat-loving insects. It is extremely important they have bright light and high daytime temperature (over 30 degrees C or more) to maintain them in proper health. Ours are in a 1 cubic metre exhibit lit by a spot lamp, which seems to be keeping them well. Humidity is not so important – they obtain the water they need from their prey and a spray of the enclosure every so often is sufficient for them.
Violin mantids are specialists on flying insects, which is why they can be kept in groups. In the wild they would feed on flies, moths, butterflies, or similar prey. Ours are being fed on house flies, which are easily obtainable. They only important consideration is that if fed wild caught insects the food has not been exposed to pesticides.
Mantids lay batches of eggs in a foam case called an ootheca, which in the case of the Violin mantis can produce about 30 nymphs, which are ant-sized when they first hatch. Young mantids will feed on fruit flies, progressing to larger prey as they mature. Although they are not cannibalistic, they need space to moult and also to ensure each has sufficient ‘air space’ around it to provide a hunting territory. They grow to be quite large – females can be over 10cm long – but they are extremely thin bodied. I am not sure of the lifespan, but I would guess 6 – 9 months or more from hatching. Females of most mantids will produce 3 or 4 oothecae once they have mated.
Mantids are such an interesting group of insects that these days there are several species available in trade. Increasingly these are from captive bred species, but some species are more difficult to care for than others and the Violin mantis is definitely one of the trickier ones. If any reader is interested in keeping mantids, I suggest they look for one of the numerous forums there are now for mantis keepers (http://www.ukmantisforums.co.uk/ is a good place to start) and as always read up on a species before you attempt to keep it.
For a video of a live Violin mantis, see here: http://www.youtube.com/watch?v=d3RPvP1OTfU&feature=related
Next week, a more standard appearing mantis, Sphrodomantis.