THE MOSQUITOES OF THE SOUTHEASTERN STATES 53 



curring in May or the last of April and a secondary peak the first 

 part of August. Rearing experiments in artificial containers at 

 Orlando have shown that, from eggs obtained in the spring, prac- 

 tically all the larvae will have reached the fourth stage and some 

 adults may emerge in about 3 months, but the remainder of the 

 larvae go through until the next year. It appears, therefore, that a 

 partial second brood occurs in this area. 



In northern localities larvae have been found associated with such 

 plants as cattail (Typha), aquatic sedges (Carex), pickerelweed 

 (Pontederia) , etc. In Florida the principal host plant is the common 

 pickerelweed (Pontederia cordata) (pi. 6, B). Larvae have also 

 been collected, in varying numbers, from the following plants, which 

 are named in the approximate order of importance: Cattail (Typha 

 latifolia and the rarer T. angustifolia) , frog's-bit (Limnobium 

 spongia), waterlettuce (Pistia stratiotes), arrowhead (Sagittaria 

 lancifolia and S. montevidensis) , spatterdock (Nymphaea maero- 

 p hy lla), and water-hyacinth (Piaropus crassipes) {99). Fortunately 

 the water-hyacinth is not a favorable host plant. Otherwise the pest 

 would undoubtedly be much more widely distributed and abundant in 

 the extreme South, where the hyacinth covers large areas of lakes, 

 bayous, and canals. 



A method for collecting the larvae is mentioned in the preceding 

 discussion of the genus Mansonia. 



The females will bite readily during the daytime in shady, moist 

 places, but the main flight takes place during the half hour just be- 

 fore and after dark. Following this dispersion they are more active 

 in the early part of the night than later. 



MANSONIA TITILLANS (Walk.) 



This is a tropical species and is found in the United States only in 

 southern Florida. It closely resembles Mansonia perturbans, and the 

 two are found in the same breeding places. The eggs are laid on the 

 under surface of the leaves of waterlettuce, and the larvae and pupae 

 are found attached to the roots of this plant only. The adults may 

 become fairly abundant and annoying locally. In 1933 larvae were 

 taken in some numbers near the Saint Johns River at the latitude of 

 Melbourne, but none could be found there the following year. Adults 

 have been taken in light traps as far north as Cocoa on the coast, 

 and several specimens have been collected in Orange County (latitude 

 about 29°). This appears to be about the limit of its northern 

 range, although its host plant occurs farther north. 



Genus THEOBALDIA Neveu-Lemaire 



(Syn., Guliseta Felt, Culicella Felt, Climacura H., D., and K.) 



Most of the species of this genus have a northerly range, and only 

 two occur in the South, these two being very diverse in appearance, 

 and neither of them important as a pest or as a disease carrier. The 

 eggs are laid in rafts, and both the larvae and the adults resemble 

 Gulex. Theobaldia inornata is placed in subgenus Theobaldia and 

 melanura in subgenus Climacura. 



