Seasonal Drift of \u3ci\u3eLethocerus Americanus\u3c/i\u3e (Hemiptera: Belostomatidae) in a Lake Superior Tributary

Drifting adult Lethocerus americanus were captured and retained by an inclined-screen smolt trap during two field seasons in the Bois Brule River, Wisconsin. Seasonal peaks of drift occurred in spring for 4 weeks following ice out and in autumn for 7 -8 weeks from mid-September through ice formation, and may have continued under ice cover when our gear was not operated. These findings are consistent with the known movement pattern of these insects to fly from lentic habitats to streams to overwinter but also suggest longitudinal movement via drift, perhaps to reach specific overwintering sites. Drift was significantly correlated with declining water temperatures in 1989 but not in 1990. Most drift occurred at water temperatures less than 12°C. There was no correlation between drift and river discharge. Drift rates were consistently low with a maximum by volume of 9 animals per 10,000 m3

New Records of Odonata from Wisconsin

Excerpt: In 1967 Mary Davis Ries published a list of 117 species of Odonata known to occur in Wisconsin, and later (1969) reported details of the distribution of species new to the state list. Collections from the Pine-Popple River in northeastern Wisconsin (Hilsenhoff 1972) added four more species to the list. Five additional Wisconsin records are reported below as the result of occasional collections made throughout the state

A Modification of the Biotic Index of Organic Stream Pollution to Remedy Problems and Permit Its Use Throughout the Year

The biotic index of the arthropod fauna of streams is modified by limiting to ten the number of individuals in each taxon used in its calculation. This reduces detrimental effects on the index of certain fairly tolerant taxa in clean streams, effects of a few tolerant taxa in somewhat polluted streams, and the effect of our inability to identify larvae in some insect genera to species. It also greatly reduces seasonal variability, allowing use of the biotic index throughout the year with only a minimal decrease in the sensitivity of the index during the summer months. The EPT index was highly variable and exhibited seasonal variation in most of the streams

New and Additional Distribution Records for Several Rare Mayflies (Ephemeroptera) in Wisconsin

One nymph and one exuviae of Acanthametropus pecatonica were collected in June 1991 from the Black River and Chippewa River, respectively. These specimens extend the known range of this rare species in Wisconsin to three large Mississippi River tributaries. Homoeoneuria ammophila was recorded in Wisconsin for the first time; nymphs were collected from the Black River and Sugar River. Nymphs of Macdunnoa persimplex, Metretopus borealis, Pentagenia vittigera, Pseudiron centralis, and Cercobrachys sp. were also encountered

Population Dynamics and Management of Deer in Wisconsin

Management of deer in Wisconsin is affected by a combination of biological and environmental factors. In the Northern Forest, winter severity dramatically affects annual survival and recruitment. However, deer density goals here are above I carrying capacity. Thus, minor errors in harvest management are in part compensated by herd responses. Deer in the farmland areas of the state are maintained at goals that for the most part are below I carrying capacity. Errors in harvest management are magnified in farmland because herd responses are not compensatory. Therefore, the harvest quotas for antlerless deer must be more precise in our farmland than in our Northern Forest. Fortunately, more precise harvest management is possible here because population trends can be more accurately monitored than in forested zones

\u3ci\u3eBaetis\u3c/i\u3e (Ephemeroptera: Baetidae) of Wisconsin

Data on life histories and environmental requirements for species in many mayfly genera remains sketchy at best This is certainly true of Baetis, which is one of the most common components of Wisconsin\u27s lotic fauna. Most Wisconsin streams that are not grossly pobted contain one or more species of the minnow-like nymphs, which are usually found clinging to surfaces of rocks or aquatic plants. Biological studies of Baetis in North America have been neglected primarily because of their enigmatic taxonomy. Even keys of Needham et al. (1935) and Burks (1953), which are considered standard referenas, are either incomplete or difficult to use when identifying Baetis

Crawling Water Beetles of Wisconsin (Coleoptera: Haliplidae)

(excerpt) Haliplidae are smail water beetles, less than 5 mm long, that frequently occur in abundance in ponds, marshes, sloughs, and swamps and also along the margins of slow streams or lakes where there is not severe wave action. Adults are readily recognized by their yelloa- to orange ground color with black maculations on the elytra and sometimes on the head and pronotum (Figs. 1,3,4). They have a distinctive shape, being broadest at the basss of the elytra and tapered toward the posterior end. The metacoxae are covered by dis~ctive plates that are unique among water beetles (Fig. 2). The tarsi and tibiae of the adults are modified for swimming, and the beetles can swim quite well, although they mostly crawl among the vegetation. Adults and larvae are found among vegetation upon which they feed, filamentous algae being the primary source of food for most species, but detrims and animal material may form a portion of the diet in some species. In Wisconsin most species probably have a one-year life cycle and overwinter as adults. Eggs are laid during spring and early summer, usually in or upon algae. There are three larval instars, and pupation takes place in moist soil above the water line. Larvae have been derrihd for only a few species, so identification is based upon adult characteristics

Gyrinidae of Wisconsin, With a Key to Adults of Both Sexes and Notes on Distribution and Habitat

More than 25,000 adult gyrinids that include 24 species were studied from all areas of Wisconsin. Dineutus discolor, Gyrinus aeneolus, G. analis, G. bifarius, and G. marginellus are lotic; D. assimilis, G. aquiris, G. confinis, and G. dichrous apparently breed in both lotie and lentic habitats; and the remaining species probably breed primarily in deep ponds or littoral areas of lakes and impoundments. Most collections were from streams in late summer and autumn because adults of almost all lentic species fly to streams to overwinter and these overwintering aggregations were easily collected. A key to adults of Wisconsin species was developed, and by using the gonocoxae and secondary sexual characters, females can be identified as accurately as males