If you’ve been keeping up with our Online Bug Encounters, you might have tuned into yesterday’s topic on parasitoid wasps. Parasitoid wasps are the true alien invaders of the insect world, hijacking the bodies of living invertebrate hosts to rear their young, much like Ridley Scott’s iconic Xenomorph.
Parasitoid wasp larvae will feed on their host until they pupate and eventually emerge as adults, at which point their host, usually living until now, finally expires. There are thousands of species of parasitoid wasps, each one specializing on a different insect order, making them an excellent form of biological pest control. Some, like giant ichneumons, are large and conspicuous, with formidable-looking ovipositors capable of drilling through wood to reach their victim, ehrr… host. Others are only noticed by the what they leave behind. In the case of aphid parasitoids, it’s usually in the form of mummies.
No, not those mummies.
Aphid mummies are the empty, bloated husks of what were once living aphids. The braconid wasps in the Aphidius genus are aphid specialists, depositing their eggs into the living body of aphid nymphs.
The wasp larvae will hatch inside the aphid, feeding on the innards while avoiding vital organs; after all, a dead host cannot provide the sustenance that a live one can. Eventually, the wasp larvae will pupate inside the aphid, ultimately killing the host in the process. Since insects do not feed during the pupal stage, a living food source is no longer necessary. Once pupal development is complete, the wasp will cut an “escape hatch” in the aphid and emerge as an adult, leaving only the aphid mummy behind.
The insect world is full of weird and wonderful survival strategies, and October is the perfect time to dive into the weirdest of them. Zombies? Vampires? The insect world has real life examples of them all, and we’ll be exploring them all month long.