Relative growth between femur and tibia in the German cockroach, Blattella germanica

Femur and tibia length of fore, mid, and hindleg, and head width were measured throughout larval stages up to the adult in both sexes. All the leg segments showed positive allometric growth against head width. Postero-anterior and disto-proximal growth gradients along the body and leg axes were detected. Total length of femur and tibia of foreleg in a particular instar was nearly equal to that of midleg in the preceding instar, and to that of hindleg in the instar before the preceding instar. Ratio of tibia length to femur length was high in hindleg, intermediate in midleg, and low in foreleg. The ratio increased as the stage advanced in mid and hindleg. Correlation coefficients between any two of the 12 leg segments, femur and tibia of both sides of the body, were calculated in every instar up to the adult stage. In all the three kinds of legs, the values between femur and femur, and tibia and tibia, of opposite side of the body were higher than those between femur and tibia of the same leg. It was also revealed that foreleg correlated more closely to midleg than to hindleg, and midleg, more closely to hindleg than to foreleg.