BREAKDOWN OF INDIRECT FLIGHT MUSCLES OF ALATE APHIDS (ACYRTHOSIPHON-PISUM) IN RELATION TO THEIR FLIGHT, FEEDING AND REPRODUCTIVE-BEHAVIOR

1. Alatae of the pea aphid, in contrast to apterae, decreased their body weight for the first 2 days after the final ecdysis. The protein content of their indirect flight muscle increased in inverse proportion to the body weight. 2. When the protein content of the flight muscles attained the maximum on day 2, alatae took off for the flight. Immediately after this, the protein content of the flight muscles and the body weight tended to decrease and increase, respectively, followed by the onset of larviposition. 3. Histological studies indicated that the decline of the protein content of the indirect flight muscles is paralleled with its breakdown. 4. When alatae were kept off the host plant after the final ecdysis, the breakdown of their flight muscles was prevented even after the flight, and few larvipositions followed. Feeding them induced both the breakdown of the muscles and the increase in body weight, followed by the onset of larviposition.