The Spiny Tachina Fly is a member of the Tachinidae Family.
large flies, growing to 1/2 - 3/4 inches in length and have black and yellow or
brown bodies which are covered with bristly hairs. Spiny Tachina Flies occupy
foothill and mountain habitats. Adults are active from late summer through
early fall and are usually found sucking nectar on plants in the aster family,
especially rabbitbrush and coyote brush.
The Spiny Tachina Fly is considered a beneficial insect since it
kills caterpillars which are considered harmful.
Females lay a small whitish egg upon the skin of a caterpillar.
This egg is glued tightly and is large enough to be readily seen by the unaided
eye. When the larva fly hatches it eats its way through the egg and into the
caterpillar's skin living inside of the body of it's host which it usually
kills. When the larva becomes full grown its skin hardens into a brown pupa
case within which it changes into a pupa. A little later the pupa changes to a
Tachina fly which breaks apart the pupa case and flies out into the world.