Table S1.

Dimensions of capsules, threads, and their attachment to the adult

Juvenile numberCapsule lengthThread length“Advantage”B + C
  • All measurements are in mm. The juveniles are designated by numbers (see Fig. 1J). The dimensions of the capsules and the attaching threads were estimated by rotating these structures into the plane of the screen (in the case of the thread, increments of the length were rotated and measured separately as necessary). The capsule length (A) was measured along the long axis, and the threads (B) were measured from the point where they emerge from the capsule to their attachment to the adult. The advantage (C) is the distance from the point at which the thread is attached to the spine measured along its length to the base of the spine (i.e., where the spine connects with the axial part of the tergite). Including the advantage (B + C) provides a measure of the maximum distance of the juvenile from the lateral edge of the “body” of the adult. In the case of juvenile 4, the thread is attached to the axis of the tergite, not a lateral spine, and the advantage was computed as negative. The correlation coefficient (Figs. S1 and S2) is higher when the advantage is included, suggesting that the size of the capsule and its distance from the lateral edge of the body may be related, perhaps implying some functional advantage in feeding. Note that in neither case does the trend line pass near the origin, suggesting that the threads may have achieved some length before the capsules began to enlarge.