A mating pair of Thanasimus formicarius (Coleoptera: Cleridae) basking in the sun on the bark of Scots pine. The males and females search for bark beetles to eat, while males appear to bump into females (attracted no more than a few cm) and immediately grab her from behind and attempt to mate. She usually lets him and then walks along (with the male on her back walking behind) looking for entrance holes of pine shoot beetles in which to lay eggs. The clerid larvae eat bark beetle larvae. The mating is for a minute or so and then guarding for several minutes. Other males that come upon the pair attempt only briefly to determine if the female is alone, and then go on their way (not aggressive). They often separate and males search for other females and females receive other males (very promiscuous).

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Images © 1996 by John A. Byers, Chemical Ecology.