National Geographic : 1989 Jun
A field guide: what to expect and when CRACK OPEN an acorn and find a world of creatures that make it their home during the nut's growth and decay. What you discover will de pend on the condition of the acorn and its surroundings. Nuts lying on dry, bare ground may not have much to show. A decaying acorn protected by a layer of moist leaf litter is more likely to house a group of interacting individuals. Acorn weevils and filbert worm moths set upon grow ing nuts during summer and early autumn; their larvae can be found in acorns freshly fallen from the tree. As the autumn wears on, increasing numbers of acorn moths, short-snouted wee vils, and sap beetles gain ac cess to acorns on the ground through insect holes, cracks, and sprouts. Parasites of spe cific insects follow their hosts inside. Some acorn varieties that wait until spring to sprout are invaded then. By summer all of last year's acorns have sprouted or been eaten in part or whole. Dead acorns usually contain a com munity of creatures, some cleaning out the decay. The husks may shelter animals for years before breaking down into humus. This guide applies to the northeastern United States, where most research on acorns has been done. If you live elsewhere, you Allacorns andpinned acorn weevil life-size; other speci mens magnified four times except microscopicspecimens. Species match those photographed. ACORN WEEVIL (CURCULIO PROBOSCIDEUS) Acorn weevil lays an egg in its drilled feeding hole; hatched larvafeeds on acorn meat. Filbertworm moth lays an egg on the acorn; caterpillar chews through the shell to feed on the meat. FILBERTWORM MOTH (CYDIA LATIFERREANA) may find many of the same animals pictured here-and probably some new ones. Gather fresh acorns and drop them into a container of water. Most with insect damage will float. Open them to find larvae, or keep them damp in a loosely covered container. Moths, parasites, T and other inhabitants will mature and emerge. To trap other attacking insects, place fresh, halved acorns in a jar and keep moist. Cover it with quarter-inch wire mesh to keep out rodents. Bury the jar, preferably under a fruiting oak tree, so that its lip is at round level. Check periodi Sfor creatures that move feed or reproduce.