Kleptoparasites 

By Norman Smith   UCCE Master Gardener 

I thought I might have a series of articles on the different types of parasitization.  In the past, I have differentiated between parasites and parasitoids.  Parasites tend to not kill their hosts (fleas and ticks), while parasitoids do.  But there are different types of parasites, perhaps not what you might call classic parasitism, where a parasite benefits from ingesting the bodily fluids of its host without killing it.  One of the more interesting forms of this unusual type of parasitization is called “kleptoparasitism”. 

The pictures are examples of insects that practice this form of parasitization: Cuckoo bees of the bee family Anthophora, Cuckoo wasps of the wasp family Chrysididae (the metallic green wasps), and velvet ants (really wingless wasps) of the wasp family Mutillidae. 

One might call these insects lazy.  Rather than go through the trouble of building a nest and catching or supplying prey/food for their young, they like to steel it from their wasp relatives.  During the process of the host wasp or bee preparing her nest, these thieves will enter the nest (hopefully while the female is out gathering food or prey) and lay an egg in the cells that they have completed, prior to her closing them off.  This egg invariably hatches before the hosts does.  The kleptoparasitic larva then either kills the egg of the host wasp/bee or lives as an ectoparasite on the outside of the larva until it dies.  Those that kill the egg will then feed on the food that the host bee/wasp has already provided - steeling food not meant for it. 

The cuckoo bee pictured has flattened hairs, probably forming a tougher skin to help them be more impervious to the hosts sting should they get caught inside the nest.  Non-parasitic bees have erect hairs, making them look hairy or wooly. The cuckoo wasps have a green integument.  Evidently, this green coloration imparts a hard integument to the wasp, again to help make it impervious to stings from the host wasp.  I have noted over the years that when trying to pin collected metallic green wasps or bees, that they are quite tough and do not pin easily.  The velvet ants also have a very hard integument as multiple bent insect pins will attest.  The velvet ants also have a very powerful sting, giving them an effective offense too.  If there is an easier way of doing something, nature will often exploit it.  Next week, a different type of parasitism.