AQUATIC INSECTS OF FRESHWATER 



FIG. 208. Water-strider or 



Skater, Hydrometra Jineata, 



Enlarged. 



water. The eggs are remarkably large for the size 

 of the insect. They are predaceous, feeding upon 

 living prey from which they suck the juices. The 

 most general species of the Eastern United States 

 are Hydrometra lineata. Fig. 208, and Hygrotrechus 

 remigis. 



Marsh-Treaders belong to the family of 

 Limnobatidae and are very slender, almost thread- 

 like insects rarely over i^ inch long, with long heads, 

 elongated thorax and abdomen, hairlike legs and of 

 inconspicuous dark color. They crawl over the 

 mud and the water surface or adhere to water plants 

 partly above the surface, feeding upon the eggs and 

 small larvae of insects and snails. The most 

 generally distributed species are Limnobates lineata. 

 Fig. 209, and the allied Limnopus rufoscutellatus. 



Aquatic Plant-Lice belong to the family of 

 Aphididse, commonly known as Aphides, small 

 soft-bodied winged or wingless insects, with oval- 

 lobed bodies, small heads, distinct eyes, filiform 

 antennae and six legs; which when winged have two 

 pairs of lace-like membranous wings. At the tip 

 of the abdomen there are usually a pair of cauda or 

 upward protruding air breathing tubes. They are 

 usually viviparous and feed upon juices by means of 

 a three-jointed piercing and sucking beak inserted 

 into the tender portion of growing plants. The most 



general species of Aphides which the 

 aquariist is likely to encounter is 

 Rhopalosiphus nymphaa. Fig. 210, 

 which infests the emersed and float- 

 ing leaves of Sagittaria, Potamogeton, 

 Duckweed, Cattails, Water-plantains, 

 Water-poppies and Lilies; while the 

 last two mentioned plants also have 

 Siphonophora lilii, and two greenhouse species, Aphis lilicola and 

 Rhopalosiphus dianthi. They produce a disfigurement of the leaves and 

 cause decay by sapping the juices. 



Order Neuroptera. Of this order a considerable number of 

 families are aquatic. All have the body elongated, thin and broad, net- 

 veined membranous wings, large head with the mouth parts well developed, 



FIG. 209. Marsh-treader, 



Limnobates limata. 



Enlarged. 



FIG. no. Aquatic plant-louse, Rhopalosiphus nymphiea, 

 winged and wingless stages. Enlarged. 



257 



