Defense by a few first-instar nymphs in the closed gall of Dinipponaphis autumna (Homoptera, Aphididae, Hormaphidinae)

The defensive behavior of the aphid Dinipponaphis autumna, which forms smal l, completely closed galls on leaves of Distylium racemosum, was observed. In mature galls, in addition to tens of mature or nearly mature aphids of t he 3rd generation, there remained 3-17 1st-instar nymphs of the same genera tion, which had well-sclerotized legs and the antennae with developed setae . Despite their minority, these Ist-instar nymphs clung to experimentally i ntroduced insect larvae and stung them with their stylets. Fourth-instar wi ngpadded nymphs, the majority of the 3rd generation at the experiment, also attacked the introduced larvae, but they were readily spill from the larva e. Four out of 205 1st-instar nymphs remaining in mature galls had the next instar cuticle developing inside, indicating that they are not destined to be sterile.