The ornamental design for a children's wagon ladybug body, as shown and described.
FIG. 1 is a perspective view of the children's wagon ladybug body;
FIG. 2 is a front elevational view of the children's wagon ladybug body;
FIG. 3 is a rear elevational view of the children's wagon ladybug body;
FIG. 4 is a side elevational view of the children's wagon ladybug body, the opposite side of which is an identical mirror image;
FIG. 5 is a top plan view of the children's wagon ladybug body; and,
FIG. 6 is a bottom plan view of the children's wagon ladybug body.
The broken lines showing of certain features, including the license plate, safety pole, seat, wheels, handle, spots, eyes, and antennae are for illustrative purposes only and form no part of the claimed design.