78 Eighteenth Report State Entomologist of Minnesota — 1920 



Patch) on the ehn ; D. fasciolus feeds on Aphis sorbi Kaltenbach of 

 the apple, upon Schisoneura cratacgi Oestknid on Crataegus, and 

 upon Phyllaphis fagi (Linn.) of the beech. These species are per- 

 haps the best known, but others present equally interesting biological 

 aspects. Several of the species live on conifers where they appear 

 to be associated with ajjhids and other small soft-bodied insects which 

 infest such trees. D. pinicola feeds at least in part on the pine-bark 

 aphid. Clicniics pinicorficis Fitch, while D. mibilits occurs on the 

 same tree and most probably has similar habits. D. laricicola appar- 

 ently breeds only on larch. Larix larlcina, and when caged on suc- 

 culent growth was found to feed on sap of the plant, altho it may 

 well be predaceous in part, when opportunity permits, as is true of 

 several species in the genus. 



The nymphs of Deraeocoris present at least two characteristic 

 forms. One group comprises several species in which the nymphs 

 are typically covered with a white, powdery, flocculent material, and 

 are thus in the early instars, not readily distinguished from the aphids 

 among which they live. Nymphs of a second group, represented by 

 D. albiguhis, nigritulns, pilosus, and related species, are distinctly 

 hairy and not covered with the white powdery substance as the above 

 mentioned forms. The first group is composed of species which are 

 known to be largely predaceous while the second group may prove 

 to be forms which are primarily phytophagous. 



The life histories of the species present some interesting varia- 

 tions. The ncbulosus group, or subgenus Camptobrochis, comprising 

 most of the species with punctate scutellum, contains forms that are 

 known to pass the winter in hibernation as adults. The species of this 

 group which have most frequently been taken in hibernation are D. 

 ncbulosus, iiiihilits, and citncatiis. Such a cycle is not the mode of life 

 for D. grandis, aphidipliagns, bctidac, pinicola^ 3.nd several other closely 

 related species, for the writer has closely observed the disappearance 

 of these insects at the end of their season and no pinned specimens 

 have been noted which would indicate the contrary. Just how and 

 where the eggs are laid are facts still awaiting investigation but the 

 writer has repeatedly found the young nymphs of D. aphidiphagus in 

 the curled elm leaves very soon after the leaf is rolled by the aphid 

 Schhoneura anicricatia Riley. The eggs are doubtless inserted in 

 the buds or twigs of the tree and upon hatching the young nymphs 

 probably travel about seeking until they find leaves which are infested 

 by the aphids. 



For the loan of material the writer is indebted to the authorities 



