23 
on a small area near the river at Central Fortuna is said to have 
resulted in a noticeable decrease in changa injury. Nymphs or adult 
changas are not killed even by complete submersion for three hours, 
and in the field all instars usually will make their way to the sur- 
face within that space of time. In laboratory tests, changas readily 
made their way to the surface through 6 inches of flooded soil, and 
once on the surface of the water they float easily, owing to their 
air-retaining, pubescent coat. Exposure for even a short time in the 
field will give insectivorous birds, such as the martinete, ample op- 
portunity to devour them. Although active swimmers, probably few 
of the insects will escape the watchful eyes of the water birds. 
In four laboratory tests clusters of changa eggs, either newly laid 
or almost ready to hatch, failed to survive a submersion of 24 hours. 
The checks hatched normally. 
Poison halts. — Poison baits against the changa are most successful 
upon small areas, such as garden plats. The cost is an important 
objection to their use over larger areas, although they have been 
found practicable by large tobacco planters. Success depends on hav- 
ing the land so clean of all vegetation that when the bait is applied 
the changas will be hungry enough to accept it greedily. As the 
native grasses are among the mole cricket's favorite food plants, 
clean culture applies to the grasses as well as to crop remnants. 
The most satisfactory bait yet found is a dry mixture of 3 per 
cent Paris green with cheap flour. Flour of the poorest quality, even 
that ruined by weevils and moths, is satisfactory for this purpose, 
corn meal, cottonseed meal, and bran making good substitutes, though 
flour seems to be preferred by the changa. Barrett (2, p. 16) re- 
ported very satisfactory results from the use of a mixture of grass 
stems, molasses, and Paris green. The Paris green and phosphorus 
mixture used against crabs is said to be acceptable to changas as well. 
The Paris green and flour bait may be applied in a shallow trench 
around the young plant at a distance of an inch or more from the 
main stem, it may be introduced into a changa gallery where it 
approaches the surface, or it may be spread broadcast over the land. 
The last method is applicable to especially heavily infested lands. 
After the area to be treated has been kept clean of vegetation for 
three or four days, the mixture should be applied, preferably in the 
late afternoon, at the rate of 300 pounds to the acre. The crop may 
be planted three to five days after spreading the bait. This treatment 
on cabbage beds at the Mayaguez station resulted in 50 per cent 
better stand on the treated plats than on the checks. The broadcast 
treatment has the added advantage of killing other injurious plant- 
feeding insects, such as other crickets and cutworms. 
