The ovipositional orientation of an aphidophagous ladybird beetle, Propylea dissecta (Mulsant) (Coleoptera: Coccinellidae) in terms of geo- and photo-taxis, colour and texture of substrates was studied. The beetle exhibited a high preference for negatively geotactic substrates for oviposition. There was no clear preference for positively or negatively phototactic substrates. When studied in combination, it was observed that substrates that were negatively geotactic were preferred over other substrates regardless of the phototaxis. Red was highly preferred over the other 5 colours tested, and plastic was the substrate of choice for P. dissecta oviposition.

Vertical migration by infective larvae (L3) of 3 species of nematodes was investigated. Upright truncated agarose cones were used to test upward migration, and comparable truncated cone-shaped agarose hollows were used to test downward migration. Flat agarose plates were control surfaces. When placed at the bases of upright cones, 74% of Ancylostoma caninum L3 migrated up, whereas only 16·5% migrated down the indented cones; this latter value was not significantly different from larval migration on flat plates. Strongyloides stercoralis L3 also migrated upward in significant numbers (80%). These larvae also failed to migrate downward under normal conditions. However, when the bottoms of the indented cones were 3–5 °C warmer than the tops, 75·5% of S. stercoralis L3 migrated down. In contrast, Haemonchus contortus L3 showed no tendency to crawl up or down cones, when compared with normal crawling behaviour on flat plates. Thus, L3 of A. caninum and S. stercoralis exhibited negative geotaxis, crawling against the pull of gravity, while H. contortus did not. The biology of these parasites may explain these behavioural differences.