8 Lake Maxinkuckee, Physical and Biological Survey 



ORDER EPHEMERIDA 



THE MAY-FLIES 



The May-flies are probably the most important insects in rela- 

 tion to the fishes of the lake. Their eggs are laid in the water, 

 the larvae are aquatic, and both are fed upon by fishes. The May- 

 flies themselves, at the close of their brief lives, fall upon the sur- 

 face of the lake by the millions and furnish a vast amount of food 

 to many species of fishes. 



Early in April the May-fly larvae begin to be conspicuous about 

 the margins of the lake and in the ponds and quiet streams. They 

 were first noted in numbers on April 4 (1901), and throughout 

 the winter they were found more or less frequently in the bottom 

 dredgings. About the fourth of April, they began to crowd up 

 near the shore in great numbers with a peculiar wriggling motion. 

 On April 5 they were found in immense numbers in a ditch and 

 some small ponds near the Assembly grounds. On April 6, millions 

 were seen in this ditch and they were very plentiful in many other 

 places. They continued very abundant until about the fifteenth 

 when they began to decrease in numbers, but the larvae were noted 

 on the 19th, 20th, and 22nd. The first May-fly imago was noted 

 on May 2. The next day many were seen in the woods indulging 

 in an aerial dance. On the fourth, many were seen in the town 

 of Culver, dancing in the air. From that date they kept increas- 

 ing in numbers, while at the same time their larvae casts were more 

 and more abundant in the water along the shore. By May 17, the 

 woods were filled with insects on the wing, many of them May-flies, 

 and the larvae were abundant in windrows at the water's edge. 

 From May 18 to 21, they were noted by the millions. On May 19 

 and 20 great numbers of casts and dead adults were observed in 

 the water and along the shore, and dead or dying adults were 

 very abundant in the g]'ass and weeds around the lake. On -May 

 22, they began copulating and laying their eggs in the water, at the 

 same time being caught in great numbers by the various kinds of 

 fishes. The straw-coloied minnows snapped them up greedily. 

 We caught a number of the May-flies and threw them on the water 

 where they were promptly seized by the fishes. They continued in 

 considerable numbers until May 25, when a good many were seen, 

 but none flying, and all rather numb. Not many were seen on 

 the 26th. A few were noted in the afternoon of the 27th and 28th, 

 and on the 29th a few stragglers were seen. On the 28th one was 

 observed emerging and several noted that had just emerged. In 



