Guest Blogger Dr John Jennings explains why there is little to worry about with the sudden increase in crickets in Australia.

Guest post by Dr John Jennings, Dr John Jennings is a Senior Lecturer in Entomology, School of Earth & Environmental Sciences at The University of Adelaide. Apart from undergraduate teaching and postgraduate supervision, John is responsible for the University’s Insect Collection, is Chair of the Council of Heads of Australian Entomological Collections and a a former President of the Royal Society of South Australia.

Many of you would have noticed the recent ‘plague’ of crickets – they have been in unusually large numbers in places as far flung as Port Pirie, Renmark and Adelaide in South Australia, and in Mildura and other north-western Victorian towns . To see large numbers of crickets in shopping malls and buildings such as the State Library in Adelaide is very unusual.

Over the last few weeks, many people have been ringing local radio stations and contacting pest controllers to find out what is going on and how they can get rid of them!

To work out what is going on, we need to go back to the autumn of 2010 when that year’s adults were depositing eggs in the soil. A mild winter allowed more than the usual very low number of eggs to survive. Each female probably lays around 200 or so, so instead of maybe two or three, several survived. These eggs then hatched into nymphs in late winter early spring and started to feed on the roots of plant, primarily grasses. In a normal year, many of these nymphs would not survive when food starts to decline and the climate becomes hotter and drier. However, the milder summer and more frequent rain events kept the food supply going, so more survived to become adults.

Over the last few weeks, the crickets moulted and became adults in much larger numbers than usual. Because they began as eggs in Autumn 2010 at about the same time, their life-cycle events all took place at about the same time.

Live crickets in cages

So, it is a conjunction of favourable events that has lead to the ‘plague’ of crickets.

Finally, whilst the crickets can be a pest in the nymphal stage when they eat grasses in pastures, lawns, etc, there is little to worry about with the adults. They are coming to the end of their life and once the eggs are laid, they will die.

Some interesting cricket factoids:

1. The male cricket makes the ‘chirping’ noise by running the top of one wing along a row of tiny teeth at the bottom of the other wing.
2. Crickets make different songs including a calling song attracts females and repels other males, and which is fairly loud, and a quiet courting song.
3. Crickets chirp at different rates depending on their species and the temperature of their environment. Most species chirp at higher rates the higher the temperature.
4. Crickets are popular pets in various parts of the world, and are often considered good luck. In China, crickets are kept in cages (see photo).
5. Chocolate coated crickets are edible and delicious.

Guest post by Dr John Jennings, if you would like to contribute your research to a guest blog on The Environment Institute Blog email environment@adelaide.edu.au.

Listen to John Jennings being interviewed on ABC Central Victoria talking about the cricket plague.