190 Annals Entomological Society of America [Vol. VII, 
the host plant which follows an infestation of the pest. A 
large number of maggots in a ripe pumpkin cause decay more 
rapidly than a smaller number in a similar host of the same size. 
The following table shows a comparison of the rate development 
of the pest in rapidly and slowly, decaying, food plants: 
TABLE It. 
COMPARISON OF THE RATE OF DEVELOPMENT OF THE MELON FLY LARV4Z IN RAPIDLY 
AND SLOWLY DECAYING HOSTS. 





Rapidly Number | Larval | Slowly Number | Larval 
decaying of period || decaying ot period 
hosts larve (days) | hosts larvee (days) 
211 7 1 4 
201 434 52 5 
Pumpkins. 0.015 - +. 55 584 || Pampkim..... c.0.. 26 6 
6 634 8 a 
1 8 
4 5 4 8 
1 6 | 45 
Bee planitmews: ) eee i 7 Beorplanicassee see rr a 
38 8 | 1 11 
Cucumber. . 2.0.02. | a Gneumberss see. 6 9 






It is possible that the rap'd decay of vegetables is caused 
not only by the enzymes secreted by bacteria, but also by the 
enzymes of the sal va of the melon fly larve. The enzymes 
change the pulp into a thick liquid and it may be possible that 
the maggots absorb some of this food directly through the body 
wall. Larve swallowing and possibly absorbing liquified food 
probably would require less time to complete their development 
than maggots feeding upon solid food. 
19. The effect of drying food on the larve.—tIn string beans 
which gradually dry up during an infestation, there is a marked 
individual variation in the growth of the melon fly larve, even 
when hatched from the same batch of eggs. In a dried, bean 
pod the larval period is longer than in a decaying one. In the 
laboratory the maggots often died in the seeds and the pods 
of dried string beans, a fact that was also observed in the field. 
In all probability, these larve died from lack of moisture due 
to the drying up of the string beans. 
