After exposure of nymphs of some Pyrrhocorid bugs to contact with certain papers or wood chips, abnormal adults are produced. Some have crumpled wings (distorted adults) and a proportion of these do not berrd, others have wing buds resembling those of a last-stage nymph and can never breed (juvenile adults). A study was made on Pyrrhocoris apterus L. and Dysdercus intermedius Dist. of the source of the factors causing these abnormalities, which were more severe in the latter species.

Exposure of nymphs to paper fro the Scientific American or the Sunday Express resulted in the production of 60–100 per cent. ‘juvenile’ adults, the others showing lesser deformities. Chips from the Baisam Fir (Abies balsamea) resulted in almost 100 per cent. ‘juvenile adults’ in Dysdercus and over 80 per cent. distorted adults in yPyrrhocoris. Chips from two other common American pulp trees (Pseudotsuga taxifolia and Tsuga albertiana) resulted in only a few distorted adults and no ‘juvenile adults’. Several chemial pulps were tested but none caused deformities, and it was conculded that the chemical processes removed all the active priniciples, even from the wood of the Balsam Fir. Mechanically produced pulp from the Balsam Fir was, in contrast, fully active. It was conculded that daily newspapers may contain enough mechanical pulp from active woods to produce the deformities, but that the active material must be in substances added later in manufacture to the papers used in the Scientific American, some copies of Nature, and tissues.

A number of tree products (mainly terpenoids) that are commonly added to paper in the final stages of manufacture were tested as extracts applied to filter paper. Tall oil rosin had little or on effect on the growth of either species, but it resulted in an increase in the number of eggs laid. Gum rosin had little effect on either species, except to produce a few distorted adults. Wood rosin likewise had little effect on P. apterus, but produced many distorted adults of D. intermedius, of which very few laid eggs. Bornly acetate, a common component of the tree orsins, produced some distorted adults of both species, and greatly reduced fertility in D. intermedius.

None of the qctive mqteriqls affected locusts (Schistocera gregaria Forsk. and Locusta migratoria migratorioides R. & F.) except that myrrh oil (a terpenoid) increased the rate of sexusl maturation.