Locating Food

Individually marked cockroaches in the rainforest generally home in on food via exploration and olfactory cues, sometimes arriving at fruit falls from quite long distances (Schal and Bell, 1986). Once near the food item, the cockroach's antennae and palps are used to inspect the resource; the information gathered is then used as basis to decide whether ingestion should proceed (WJB, unpubl. data). In domestic species (Blattella germanica), food closest to the harborage is exploited first (Rivault and Cloarec, 1991); this is probably also the case for cockroaches in natural habitats.

Individuals of Diploptera punctata in Hawaii are attracted to moist, dead leaves (WJB and L.R. Kipp, unpubl. obs.). Experiments were conducted on a large (2 m tall) croton bush in the late afternoon, during the inactive period of the cockroach. The insects previously had been seen foraging in the bush at 9:00 the same morning. Dead, wet leaves were placed on a branch about 1.2 m from the ground, and within 5 min individuals appeared near the bait leaves, apparently lured from their harborages at the base of the plant by the leaf odor. When "activated"by the odor they scurried about, waving their antennae. When a branch route took them near, but not to the dead leaf, they would get to the end of the branch, antennate rapidly, then turn and run down the branch to seek another route. Sometimes an individual made several attempts, over various routes, before locating the wet leaf.

They were never observed flying to the bait. In Hawaii, D. punctata foraged from early evening (6:00 p.m.) to mid-morning (10:00 a.m.), with two peaks in activity at 8:00 a.m. and 10:00 p.m. Nonetheless, the cockroaches could be activated to return to the above-ground portions of the plant at any time by hanging new decaying leaves within the canopy. Members of this population survived and reproduced for 6 mon in WJB's laboratory in Kansas on a diet consisting solely of dead oak and hackberry leaves.

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