This is the emerald jewel wasp (Ampulex compressa), a species of digger wasp, dragging along an American cockroach (Periplaneta americana). This rather beautiful creature is a parasitoid wasp and the life for the poor insect it in its grasp is particularly grisly and very reminiscent of the Alien films.
Firstly, the wasp inserts its ovipositor (an adapted stinger) into the thorax (between the first pair of legs) which releases a venom that immediately paralyses the hapless cockroach. This process will take less than a second with the roach being considerably bigger than the female wasp – very few male A. compressa’s have been recorded as the females reproduce using parthenogenesis (self-cloning).
The paralysis allows time for the second and more sinister venom to be injected into the brain and sub-oesophageal ganglion, which induces hypokinesia for the remainder of its short life. The wasp’s ovipositor is so sensitive and well adapted is can ‘feel’ around in the brain and locate the correct area every single time. This hypokenetic state makes the cockroach effectively a zombie unable to flee or fight the wasp, it now exists only to serve.
After the initial paralysis wears off the roach begins carefully grooming itself for approximately 30 minutes. Studies have shown that this cleaning is induced by an upsurge in dopamine in the brain. This implies that the venom has a dopamine-like component, though whether this is part of the wasp’s master plan to remove any harmful micro-organisms that might be detrimental to the larva or a mere side effect is unknown. It might be a last act of kindness by the wasp: giving its victim a euphoric high before the end.
As her host cleans, she wanders off in search of a suitable burrow to lead it to (squeamish people stop reading now). When she returns she bites of an antennae and sips some nourishing hemolyph (insect blood) which is mainly composed of carbohydrates, proteins, salts and sugars – apparently mind manipulation works up an appetite.
The ill-fated insect is then led to the burrow of doom; in the same way you would walk a dog on a leash. Once it’s there the wasp shoves it in with all the ceremony of disposing of the rubbish. A single egg is laid on the coxae of the prothoracic (mid)-leg and the wasp covers the entrance of the burrow. This act seems to be more to prevent predation than to trap the cockroach. The process takes roughly 30 mins and during that time the cockroach does nothing…. There is no mad scramble to safety or a last-ditch attempt to rid itself of its newly acquired ‘baby’. If the cockroach is deliberately separated from the tender care of A. complexa the venom wears off after approximately three weeks, but anywhere from one – four. Fascinatingly, whilst the nervous system is a depressed state the locomotion system is still functional, even elevated.
The larva hatches after two days and in a macabre act of vampirism bites a hole in the cockroach’s abdomen and feeds on the hemolyph that oozes out, it then crawls in and consumes the organs, leaving the nervous system for last. When the cockroach has been completely consumed it is finally allowed to die, the larvae starts secreting an antimicrobial aggregate onto the inside walls of the husk that was once the cockroach and after six weeks an adult female wasp emerges to repeat the process again.
Banks, C. and Adams, M. (2012). Biogenic amines in the nervous system of the cockroach, Periplaneta americana following envenomation by the jewel wasp, Ampulex compressa. Toxicon, 59(2), pp.320-328.
Gnatzy, W., Michels, J., Volknandt, W., Goller, S. and Schulz, S. (2015). Venom and Dufour’s glands of the emerald cockroach wasp Ampulex compressa (Insecta, Hymenoptera, Sphecidae): Structural and biochemical aspects. Arthropod Structure & Development, 44(5), pp.491-507.
Gal, R. and Libersat, F. (2008). A Parasitoid Wasp Manipulates the Drive for Walking of Its Cockroach Prey. Current Biology, 18(12), pp.877-882.
Gal, R. and Libersat, F. (2010). On predatory wasps and zombie cockroaches. Communicative & Integrative Biology, 3(5), pp.458-461.