NATURAL ENEMIES Of the natural enemies of Hemiptera we can only offer incom plete records as time did not permit detailed studies of this phase of the associations. The mainmals of the region, save perhaps the beavers, probably have little influence on the hemipterous fauna. The latter by the construction of dams have altered the conditions of the drainage channels and inundated rather extensive areas. As a result of the higher water level many of the plants have been smothered and replaced largely by more or less hydrophytic forms. With this transition of the vegetation there has, of course, been a change of the hemipterous content of the flooded areas.
Birds are numerous and no doubt some of the species prey extensively on this group of insects, especially during certain parts of the year but we have not observed any specific instances of especial or noteworthy attacks on particular species. Reptiles are not great in numbers and are of little importance as checks upon Hemiptera. The Batrachians, especially frogs, are quite numerous and feed largely upon insects. No attempt has been made to study the contents of the stomachs of toads and frogs of the Cranberry Lake region, but the works of Kirkland,* Surface,t Drake,t Munz § and others readily show the economic aspect of these amphibians. The fishes of course consume many aquatic insects and forms that happen to fall into the water, but they have very little relation to the forest Hemiptera,.
The predaceous Hemiptera play an important role in the control of plant-feeding Hemiptera and other phytophagns insects. Such ravenous forms as Nabis limbatus, N. roseipennis, N. rufusculus, Podis us serieventris, P. modestus, P. placidus, P. maculiventris, Anthocoris borealis, Tetraphleps osborni, Triphleps insidiosus, Deraeocoris (Camptobroeltys) borealis and the like are very con spicuous in the region studied. The aquatics are mostly predatory, but they sustain themselves upon aquatic insects and other aquatic animals and also upon insects that happen to fall in the water, Hymenopterous egg parasites were bred from the eggs of several of the Heteroptera and numerous Jassids were parasitized by dryinids. Taehinid eggs were observed on the backs of some of
the Pentatomidae. Predaceous insects in other orders also destroy many Hemiptera.
Of the invertebrate groups associated with Hemiptera the spiders are of special interest and while the species are not numerous and individuals have not been observed as specially abundant they are probably the most important of the natural enemies.
Collections of these have been made incidentally while sweeping or beating for Hemiptera and specimens have been submitted to Dr. W. M. Barrows of the Ohio State University for identification. The following list should not be considered as representing the spider fauna of the region, but simply as .indicating the most common species associated with the Hemiptera and from the known food habits * as constituting a natural cheek for this group as well as other associated insects.
Common Spiders of Cranberry Lake Region Epeira, insularis Hentz. Barber Point, no special habitat noted.
Epeira trifoltium Hentz. Barber Point, collected in the Beaver Meadow, July 30, 1920.
Epeira trivittata Keys. Barber Point: marsh, July 5 and 2S; willow, Aug. 5; tote road along Sucker Brook, July 23; virgin forest, July 2S; Aug. 11; Plains, Aug. 3-, 1920.
Epeira thadWevs Hentz. Virgin forest, Aug. 11. ]020.
Fellows /loan, Peckham. Barber Point—no special habitat noted but accord ing to Dr. Barrows this is a meadow species.
Tibellas duttoni Hentz. Barber Point, taken in the and Beaver meadow, July 5, 2S; tote road, July 28; on willows, July 28, " burn," July 28. 1920.
Tibellus oblongus (Waick). Barber Point, taken near the tote road leading to Forsaith's Bog, July 28, 1920.
nendryphantes militaris (Hentz). Marsh and meadow tote road, July 28; burn July 27; on willows Aug. 5, 1920.
Dendryphav'tes eapitatvs (Rentz). Taken on willow, July 28, in dense virgin forest; Barber Point, July 29.