Notes on the biology of the tea-tussock-moth, Euproctis pseudoconspersa Strand

Abstract

Whilst engaged in the rearing of the tea tussock-moth, Euproctis pseudoconspersa Strand, the following facts were observed and appeared to be worth noting : 1. This species breeds twice a year in Japan, but under a constant temperature, 22-25℃, it can be bred successively throughout the year under captivity. 2. Eggs are laid in batches, each contains about 120 eggs. The diameter of the egg 0.6-0.7mm, the duration of the egg development 20-22 days under above mentioned condition. 3. The number of the larval instars is usually 6-7, often 8, 9, or 10. the duration of the larval period was 46 days in average. 4. The prepupal stage takes 2 days, the pupal stage 18-23 days. The male insect pupates and emerges about two or three days prior to that of the female. 5. The length of the survival of the adult insects was 5-7 days : pairing takes place within 24 hours and in an advanced case the oviposition was observed within two days after emergence. 6. The first instar larva has no urticating spicules excepting a few ones transmitted from the egg covering. In the second instar the larva is provided with the spicule bundles on the first and second abdominal segments, each pair is arranged on the subdorsal line. Another bundles appear in the penultimate instar on the eighth segment, and in the ultimate instar there are spicule bundles throughout from the first to the eighth segment, and further each on the lateral lines. The length of an urticating spicule is from 0.03 to 0.207mm, it becomes longer in a later instar. 7. Inside the cocoon there is a brownish circular band at its anterior one third. This band is composed of numerous urticating spicules, and is more distinct of a female insect. The female moth emerges out carrying the spicules on her abdominal tuft hairs. 8. The larvae show a very strong gregarious habit. The length of the larval period as well as the number of the ecdysis seems to be evidently increased by the decrease of the number of the caterpillers fed together. 9. In the final instar the size of the larvae, as measured by the cranium, does not differ regardless the number of the ecdysis.