there is a kind of butterfly larvae eat the weeds

there is a kind of butterfly larvae eat the weeds, there are toxins that weeds toxin. After absorbing the toxins larva larvae into butterflies. If the birds eat this butterfly, it will vomit. And similar to the situation we mentioned above, this butterfly's wings also have a warning color, the birds can recognize their color, do not feed them. Well protected so that their own butterfly.

impression of seismic waves as well. About three waves. Primary, secondary, surface.

Primary (may be called the wave) was the first to reach the seismic station, and spread the fastest. Some of the surface transmission speed is 4 / 5, in the deep pass rate is 6 / 7 (with title)

Secondary and Primary comparison say, is because the vibration direction of wave propagation perpendicular to the direction. Analogy with the propagation of sound waves. Propagation speed is slightly slower because it is more complex movements (with title)