Bug FAQTherion morio
Therion morio · Order: Hymenoptera · Family: Ichneumonidae
Therion morio lays eggs that have a disc around the middle and a stalk at the end, making them look like the oil lamp from Aladdin. The adult wasp inserts these eggs into webworm caterpillars, where the first larval stage feeds through the egg membrane before emerging. It is found in North America where it lives as a parasite of the webworm caterpillar.
Source: Wikipedia
How to recognize it
Their eggs have an equatorial disc and a caudal stalk, resembling a cartoon oil lamp. Like H. fulvipes, their eggs share this disc-and-stalk shape.
Source: Wikipedia
Where it lives
It parasitizes the webworm caterpillar in North America.
Source: Wikipedia
What it eats
It feeds as a parasite on the webworm caterpillar.
Source: Wikipedia
Life cycle
Adults pierce webworm caterpillars with their ovipositor to deposit eggs inside. The egg partially hatches and the first larval stage, called a feeding embryo, consumes nutrients through the remaining egg membrane.
Source: Wikipedia
Where it comes from
Its native range is North America, where it attacks webworm caterpillars.
Source: Wikipedia
Lookalikes
Their eggs look like those of H. fulvipes because both have an equatorial disc and a caudal stalk.
Source: Wikipedia
Where it is found in the US
Recorded in 30 of 51 states and DC. Most records: Ohio, Illinois, New York, Maine, Pennsylvania, Massachusetts, Oregon, Vermont.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
How does Therion morio reproduce?
The adult inserts its eggs into webworm caterpillars using an ovipositor, and the first larval stage feeds through the egg membrane before emerging.
Source: Wikipedia
What do Therion morio eggs look like?
The eggs have a disc around the middle and a stalk at the end, resembling a cartoon oil lamp.
Source: Wikipedia
Where is Therion morio found?
It lives in North America as a parasite of the webworm caterpillar.
Source: Wikipedia
Same family (Ichneumonidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Therion_morio
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-26 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-26.