NOVELTY - Use of Plodia interpunctella is claimed for degrading polyethylene during larval period of Plodia interpunctella. Plodia interpunctella belongs to order lepidoptera, family pyralidae and subfamily phycitinae. Plodia interpunctella is a grain phralidid caterpillar.    USE - Used for degrading polyethylene during larva period of Plodia interpunctella (claimed).    ADVANTAGE - The Plodia interpunctella larva directly degrades pure polyethylene by digesting it without using any additive, and doesn't cause any environment pollution.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) method for culturing Plodia interpunctella, which involves collecting and separating Plodia interpunctella from wheat, barley, maize, beans, peanut, dried fruit, powder grains, milk powder, Chinese medicinal plant, barn or corn to obtain Plodia interpunctella imagos, incubating obtained imagos in an artificial climate chest at 25-30 degrees C and with 50-80% of relative humidity to spawn, detecting the ova by an anatomical lens after incubating Plodia interpunctella for 1-2 days, storing ova of Plodia interpunctella in a refrigerator at 4-5 degrees C, collecting ova once every day until all of them spawn, placing them in a sterile petri dish paved with a wet filter paper or an absorbent paper and incubating Plodia interpunctella at 20-35 degrees C temperature and 25-100% relative humidity; and    (2) a method for degrading polyethylene by Plodia interpunctella larvae, which involves placing 150-300 incubated Plodia interpunctella larvae in 100-350g of hulled grain, maize, barley, wheat or peanut foodstuffs and placing them in a polyethylene plastic bag, which is 0.019-0.07 millimeter thick and 17-25 x 26-34 square centimeters large, culturing Plodia interpunctella in an artificial climate chest at 16-35 degrees C and with 25-100% of relative humidity, naturally irradiating and keeping Plodia interpunctella in dark place, the larvae starting to gnaw at the polyethylene plastic bag from 10th-15th days of the growth until they are pupated at 35th-55th days, discharging the degraded product via excrement, detecting the excrement by a Fourier infrared spectrometer and a high-temperature gel permeation chromatograph for determining the degradation.