The thoracic segments have one ganglion on each side, which are connected into a pair, one pair per segment. This arrangement is also seen in the abdomen but only in the first eight segments. Many species of insects have reduced numbers of ganglia due to fusion or reduction. Some cockroaches have just six ganglia in the abdomen, whereas the wasp Vespa crabro has only two in the thorax and three in the abdomen. Some insects, like the house fly Musca domestica, have all the body ganglia fused into a single large thoracic ganglion. COUNT 5
QSN1 What is on each side of a thoracic segment? ANS1 ganglion QSN2 How many ganglia are on each side of a thoracic segment? ANS2 one QSN3 Ganglia are connected into a what? ANS3 a pair QSN4 How many pairs of ganglia are in a segment? ANS4 one pair QSN5 What other location on an insect are ganglia located? ANS5 abdomen