Adult mayflies are commonly found in the vicinity of water, often in huge mating swarms. They are short-lived creatures, existing for only a few hours (mostly nocturnal species) or a few days. A swarm consists generally only of males, often in the thousands, flying in an up-and-down pattern over water or a specific marker such as a rock, bush, or shoreline. Swarming commonly occurs at dusk in temperate species, light intensity and temperature being the major determinants of when it occurs. Females enter a swarm, and mating usually occurs immediately and lasts for less than a minute. Parthenogenesis has been reported for about 50 species, though it is rarely obligate. The egg-laying habits are quite varied, as is the number of eggs laid (generally from 500 to 3000). In some short-lived species eggs are laid en masse on the water surface. The clutch breaks up and the eggs sink, becoming scattered over the substrate. In species that survive for several days the eggs may be laid in small batches; Baetis spp. females descend below the water surface to secure the eggs on the substrate. Eggs often have special structures that serve to anchor them in position. They usually hatch within 10-20 days, but in a few species the eggs enter a diapause to overcome low winter temperatures. Consequently, they do not hatch until the following spring. In some species that have a relatively long adult life (up to 3 weeks) ovoviviparity occurs, females retaining fertilized eggs in the genital tract for several days prior to oviposition. Embryos then hatch from the eggs within a few minutes of deposition.

In most mayfly species the larval life span is 2-4 months; however, some mayfly larvae are long-lived, with a development time of at least a year and, in some instances, of 2 or 3 years. During this period they molt many times (15-30 is most common, but as many as 50 have been recorded). Larvae occupy a wide range of habitats, though each one is characteristic for a particular species. They may burrow into the substrate, hide beneath stones and logs, clamber about among water plants, or cling to the upper surface of rocks and stones in fast-flowing streams. With the exception of a few carnivorous forms, larvae feed on algae, or plant detritus, and thus play a key role in energy flow and nutrient recycling in freshwater ecosystems. Populations oflarval mayflies show characteristic movements at specific times during their life. These may be diurnal, seasonal, and/or directional. For example, species in running water may have daily migrations into and out of the substrate, or they may move into the substrate during periods of heavy water flow. Typically, in both still and moving waters larvae move toward the shore during the later stages of their existence. And some species, especially of Baetis, have characteristic nocturnal rhythms of downstream drift. For other species, drift is influenced by both larval characters (e.g., age and population density) and environmental factors such as temperature, oxygen, current velocity, sediment, and food. How species compensate for the potential decrease in population upstream is not well understood, though for some upstream movement of larvae has been demonstrated, while for others the imagos undertake upstream flights before oviposition.

Mayflies are unique among living Pterygota in that they molt in the adult stage. A mature larva, on leaving its aquatic environment, molts into a subimago, a winged adult form (but see Chapter 2, Section 3.2), often capable of flight. A subimago can be distinguished from the imago into which it molts by its duller coloration and by the translucent wings, which are often fringed with hairs. A subimago exists usually for about 24 hours before molting to the imago. Under adverse conditions, however, a subimago may survive for many days. In a few exceptional species the subimago never molts but is the reproductive stage. It has been speculated that the adult molt may be a primitive trait retained because of a lack

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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