You may have seen them in your trees, they especially like deciduous forests. They're called the American Dagger Moth caterpillar
BayToday reader June Smith writes, "So we have seen two of these yellow fluffy cute caterpillars but with black spikes and apparently they are mildly poisonous, depends on the person who touches them. Daughter lives a few blocks away and seen three recently."
The American dagger moth, like June's, can be seen from April to September in deciduous woodlands and forests.
And while there are reports of the hairs sometimes causing skin irritation in humans, there is no evidence that they contain any form of venom.
If you do handle one of these caterpillars and get a rash, wash the affected area with soap and water to remove any loose spines or hairs. Dry with air, not a towel and use sticky tape to remove any remaining spines or hairs. Apply rubbing alcohol and then ice.
