Four types of vibration behaviors in a mole cricket.

Vibrational communication is known in some subterranean insects. Except for their use in sexual signaling, vibration behavior has rarely been reported. We report here four distinct types of substrate-based vibration behaviors in the mole cricket, Gryllotalpa orientalis, which are not associated with sexual signaling because of the occurrence of these behaviors in nymphs: (1) scraping with the forelegs; (2) foreleg taps (tapping with the forelegs); (3) palpal taps (tapping with the maxillary palpi); and (4) tremulation (back-and-forth movement of the whole body). Scraping is hypothesized to be used for the inspection of borrows. Foreleg taps are possibly informing nearby individuals of their presence, because it is never observed in solitary conditions. Palpal taps are rarely observed and its function is unknown. Tremulation is possibly related to avoidance of conspecific individual approaching and touching. The combination of the four vibration behaviors in the mole cricket may be unique among insects.

Observation of the second harmonic in Thomson scattering from relativistic electrons.

A free relativistic electron in an electromagnetic field is a pure case of a light-matter interaction. In the laboratory environment, this interaction can be realized by colliding laser pulses with electron beams produced from particle accelerators. The process of single photon absorption and reemission by the electron, so-called linear Thomson scattering, results in radiation that is Doppler shifted into the x-ray and gamma-ray regions. At elevated laser intensity, nonlinear effects should come into play when the transverse motion of the electrons induced by the laser beam is relativistic. In the present experiment, we achieved this condition and characterized the second harmonic of Thomson x-ray scattering using the counterpropagation of a 60 MeV electron beam and a subterawatt CO2 laser beam.