To see how being in a dirty environment affects the grooming behaviour of the insects, place a little chalk dust into the petri dishes containing the four original blowflies. Repeat the measurements made in 4. Use a chi-squared test to compare the frequencies of the various grooming elements in the four clean and four dirty flies. The following are some of the behaviour patterns that should be seen in blowflies. Metathoracic legs plus one mesothoracic leg.
Dirty flies groom more than clean ones.
The experiments are best done in pairs so that one student makes the observations and the other records them. This is generally a very reliable practical. Animal Behaviour 29, 973-984. In this set of practicals, visual displays are described and analysed. Genetic effects and the existence of reproductive isolating mechanisms can be studies by using different strains of fruitflies.