Photo: Jeff Gruber & Nicolas Gompel
The beetle, Helichus striatus, has hydrofuge hairs that hold the plastron (air bubble) in place. If the plastron is lost, the hydrophobic nature of the hairs dissipate and the hairs become hydrophilic. The hydrophobic coating must be replaced.
Beetles that lose their plastron will climb on sticks to the surface and begin grooming. The hydrophobic substance appears to come from beetle salivary secretions. The beetle has brush-like hairs on…
Source: Living With Insects Blog