THE BLACKHEAD FIREWORM OF CRAXBERRY. 9 
on the Pacific coast. On those which are not quickly and easily 
drained this winter water remaining on the bog late in the spring 
causes the vines . and the fireworm eggs to be rather slow in de- 
veloping, with a consequent grouping of the hatching and develop- 
ment of the first generation of larvae. 
THE LARVA. 
The newly-hatched larva of the blackhead fireworm (fig. 2, a) is 
about 0.1 mm., or a little over one-thirty-second of an inch in length; 
at first it has a pale yellow color which turns to a darker yellow with 
age, and has a relatively large dark brown or black head, accentuated 
by the thoracic shield, the first segment back of the head, which is 
nearly as dark as the head; hence the name " blackhead.*" 
Fig. 2. — The blackhead fireworm : Views of the larva, enlarged 7.5 times : a, Newly 
hatched larva? : ~b, dorsal, lateral, and ventral views of full-grown larvae. 
When fully grown (fig. 2, b) the larvae measure about 6.5 mm., or 
about one-fourth inch in length, and are dark greenish yellow with a 
coat of darker olive green above. The head and thoracic shield 
are black. The larvae are very active from the time they are about one- 
fifth to one-fourth grown and vigorously wriggle from their gal- 
leries when disturbed, falling to the ground and quickly concealing 
themselves among the trash and leaves beneath the vines by a char- 
acteristic sidewise and backward movement of the body. They are 
provided with three pairs of thoracic legs, four pairs of abdominal 
legs, and one pair of anal legs. Depending upon the weather and 
the time of the season, the blackhead fireworm spends from 10 to 
about 75 days in the larva state. 
74890°— 22 2 
