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Giant Ichneumon Wasp
Megarhyssa atrata
44.8012, -68.7778
Field Notes
Description:
The life cycle of Megarhyssa atrata begins when a female lays her eggs in the burrow of a pigeon horntail larvae between the months of June and September. Eggs act as ectoparasitoids and are oviposited directly on the host larvae, one egg per host burrow. While still inside the eggs the Megarhyssa atrata develop into larvae. Upon hatching, the larvae emerge and begin feeding on the host larva from which they obtain all of the nutrition they will ever need during their short lifetimes.
These wasps remain in their larval form throughout the winter, continuing to feed on their host meal. In the spring they pupate within the horntail larva burrow, undergo a complete metamorphosis, and emerge from their burrows as adults between the months of June and September. Once the wasp emerges it will live for up to 27 days, just long enough to mate and continue the cycle.
Lifespan-- After emerging from pupae, adult Megarhyssa atrata live an average of 27 days. However, many Megarhyssa atrata will never leave their burrows. Although it is a short time span, there is a high mortality rate in this species between metamorphosis and emergence.
Habitat:
Found (Native) in northeastern and central United States and Southeastern Canada.
The entire life cycle of Megarhyssa atrata occurs within the confines of the deciduous forests of central and northeastern North America. Megarhyssa atrata is a parasitic species that requires a host which provides nutrients to developing larvae. Deciduous forests include several hardwood tree species that are home to the preferred host: pigeon horntail larvae. Pigeon horntail larvae develop inside decaying hardwoods during the winter, and Megarhyssa atrata seeks out these locations to oviposit. The Megarhyssa atrata cycle begins when the females oviposit their eggs in either decayed logs, fallen trees, or stumps where the larvae of pigeon horntails have burrowed into the wood. Burrows chosen as egg-laying locations have often been invaded by fungus and rot, making it easier to insert the ovipositor.
Notes:
These insects were approx. 2 inches long (?) with maybe 4 inches for their tendril (ovipositer), they insert into the tree. They were not concerned with my macro photographing. Nothing I read says that they sting, or cause any harm to humans, though they certainly are intimidating to see (at least the females are!)
The only difference I saw between my wasp and the one on the website I looked at was the wing color. The wings of the wasp on the website looked blacker in color. My wasps have simply "tinted" wings.
SOURCE: (I suggest reading it if you want to learn more about these interesting wasps.)
http://www.inaturalist.org/taxa/47941-Megarhyssa-atrata
http://www.youtube.com/watch?v=MEfBhl9ovA4
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