The hygroreaction of the larvae of the Oriental rat flea Xenopsylla cheopis Rothsch. (Siphonaptera: Pulicidae)

The humidity reaction of the larvae of Xenopsylla cheopis Rothsch. was studied in an air-chamber with a 0–100% relative humidity gradient. Highly significant differences ( P < 0·001) between the reactions in the various R.H. ranges was found. The most preferred relative humidity along this gradient was 100%. Relatively few larvae were collected at each R.H. in the range between 0 and 90% R.H. The reaction of the larvae under the experimental conditions was seen to be of orthokinetic type.