THE POTATO TUBER MOTH, 
39 
larva seldom escapes. The parasitized tuber-moth larva is readily de- 
tected when it becomes mature and seeks a place to pupate. A large 
dark or reddish spindle is apparent, filling most of its abdomen, and the 
larva is very restless and seldom stays in one 
place long enough to spin a cocoon. Finally 
the host loses all power of locomotion and dies, 
and within a few hours the mature parasite 
larva (fig. 26) forces its way through the skin of 
its host and begins spinning its cocoon (fig. 27) • 
As the parasite larva is almost the size of its 
host, only one develops on each tuber worm. 
The cocoon is completed within a day or two. 
It is very heavy, ellipto-cylindrical in shape, 
light gray, and with a lighter band around the 
middle. The pupa, 
removed from its co- 
coon, is shown in fig- 
ure 28. 
This parasite assisted greatly in reduc- 
ing the numbers of the tuber moth in the 
potato tops during 1914 and 1915. 
An average life cycle is given below: 
December 15, 1914. — Tuber-moth larva parasitized 
by Campoplex phihorimaeae . 
February 5, 1915. — 1 Campoplex phihorimaeae adult 
issued. (Male.) 
February 6, 1915. — 1 Campoplex 
phihorimaeae adult issued. (Female.) 
Life cycle 52 days at an average 
Fig. 26.— Campoplex phthori- 
macac; Lateral view of ma- 
ture larva with view of face. 
Much enlarged. (Original.) 
Pig. 27.— Cocoon of Campoplex phtho- 
rimaeae, parasite of potato tuber 
moth. Much enlarged. (Original.) mean temperature of about 54° F. 
HABROBRACON JOHANNSENI VIER. 1 
This is probably the best known parasite of the 
tuber moth, both where it occurs as a leaf-miner and 
as a pest of stored potatoes. It is well distributed, 
having been reared from tuber-moth material collected 
over most of southern California. 
It oviposits in the mature larva of the tuber moth 
after it has spun its cocoon. As many as 13 parasite 
larvae have been observed to develop on a single host. 
The adult female is very active, but seems to prefer 
to work only in the fight, for the parasite has never 
been reared from material kept in darkened bins. 
The larvae may develop either externally or internally, the host 
seeming to depend on the position of the egg. After the tuber-moth 
Fig. 28.— Campo- 
plex phthorimaeae: 
Lateral view of 
pupa. Much en- 
larged. (Original.) 
Chittenden No. 2230 04 . 
