THE MELON PLY. 
9 
the crown of the plant, and the larvae, on hatching, feed there first. 
They later burrow down into the taproot and upward into the 
petioles of the leaves, and even into any young runners that are form- 
ing. The capacity of the melon fly for injuring a watermelon seedling 
is shown in figure 6 (p. 6). The enlarged figure of the root shows 
four full-grown larvae eating their way into the root. In the figure 
of the seedling the larvae have almost severed the leaf to the left, 
and have tunneled completely through one of the petioles and so 
destroyed it that the weight of the leaf has caused its stem to break 
over. Injury to a seedling runner is shown in figure 8. In cer- 
tain places in Hawaii where the melon fly is very abundant, entire 
Pig. 8. — Seedling watermelon showing runner killed back by burrowing melon-fly larvae. 
(Authors' illustration.) 
fields of watermelons may be killed before the plants can develop 
runners. Squash, pumpkin, cucumber, tomato, and bean seedlings 
almost never are attacked. Larvae never are found in the roots of 
older plants. 
INJURY TO THE STEM. 
As the plant becomes older, , it is still subject to attack. The female 
fly lays her eggs in the rapidly groAving pumpkin and squash vines, 
but the larvae after hatching do very little damage, although they are 
able to mature. They often cause abnormal swellings or cancerlike 
spots where a colony of them are feeding, as illustrated by figure 7 ; 
but if the injury threatens the stem, the plant throws out roots on 
either side of the part affected to offset the damage. Such attacks 
upon the stem are not of importance, except in the case of watermelon 
and cantaloupe. 
18314°— 18— Bull. 643 2 
