The poison-glands of the sting in wasps and bees are well-known examples of these.
Hornets, bees and wasps of many varieties abound.
The chief points in the life-history of Stylops and Xenos, which are parasitic on certain bees (Andrena) and wasps (Polistes), have been investigated by K.
These are very simple, open and generally regular flowers, white, greenish-yellow or yellow in colour and are chiefly visited by insects with a short proboscis, such as short-tongued wasps and flies, also beetles and more rarely bees.
It is noteworthy, however, that although the manner in which the prey is stung (for example) is on the whole similar in the case of the members of any given species - that is to say, all the wasps of the species behave in very much the same manner - yet there are minor variations in detail.