In general, black fuzzy caterpillars are not poisonous. However, the Bag Shelter Caterpillar, which has a black and iridescent-blue fuzz is one of the most poisonous caterpillars in Brazil and Venezuela. In addition, the White Hickory Tussock Moth Caterpillar, a fuzzy black-and-white caterpillar found in the United States and Canada, excretes venom when touched.
The White Hickory Tussock Caterpillar lives in large parts of Canada and the United States. Most years, it only appears between June and September. In 2011, rumors began circulating the Internet that these caterpillars were poisonous. Although the rumors were rather alarmist, the fact that these caterpillars excrete venom was true. After handling them, many people get rashes, and some people experience severe symptoms such as swelling and nausea.
Most venomous caterpillars are stinging caterpillars, and they have hollow hairs connected to poison sacs beneath their skin. When these hairs are touched by a human, they pierce the human's skin and allow the venom to flow through. Buck Moth Caterpillars, lo Moth Caterpillars, Puss Caterpillars, and several other species are stinging caterpillars found in the United States, but none of them are black and fuzzy.
If someone is stung, he should use special tape to remove any lingering caterpillar hairs, then wash the area with soap and water to minimize infection.