14 BULLETIN NO. 4, DIVISION OF ENTOMOLOGY. 



the larva as soon as it breaks the shell, or, indeed, in the egg. As the 

 surface water is always warmest, it should be retained as long as pos- 

 sible and the cooler water drawn off from beneath. This can be easily 

 done by building a second gate, not reaching to the bottom, outside the 

 main gate, at a distance of about one foot from it. The water will rush 

 in from below, rise to the level of the inside gate, and overflow with- 

 out materially disturbing the surface water. This plan has been pur- 

 sued by Dr. Brakeley, and on his bogs I had a chance to test it. May 

 22, the water had been about half drawn off, it having reached a tem- 

 perature of 80° two inches from the surface. On that day I examined 

 for eggs and larvae in various portions of the bog. Where the water 

 had not touched, the larvae were abundant and half grown ; where the 

 water had covered, but had been off a week, no larvae were found, and 

 but few perfect eggs; while, on the contrary, many eggs in which were 

 fully developed and defunct larvae were found. Still there were eggs 

 enough left to furnish a very respectable lot of larvae, as will hereafter 

 appear. Going down close to the water line many eggs were found 

 largely containing fully developed but dead larvae, but some also liv- 

 ing ; a few instances were seen where the larva had hatched beneath 

 the water, had lived and eaten between the surfaces of the leaf for a 

 day or two, and had then succumbed. One instance was noted where 

 the larva was yet alive, and in the cavity in the leaf. This use of the 

 water is not of course as successful as the first plan suggested, for 

 while it destroys a large number of insects in embryo, a large number 

 escape, owing to the difficulty of raising the water on an unequal bog 

 to a sufficiently high temperature. Many bogs have 10 to 12 feet ot 

 water at the gates, and the vines at the edges scarcely covered ; of 

 course the deeper parts of the bog will not be warmed for a long enough 

 time to force the development of the larvae beneath the water far enough 

 to destroy them, and many will thus escape. On a level bog, where the 

 water covers the vines but a few inches, there is much greater hope of 

 complete success. 



On June G, 1 again visited the bogs, and for several days experi- 

 mented with insecticides. I found on those portions of the bog which 

 had not been flowed full-grown larvae, some pupae, and a few imagos; 

 on the portions which had been flowed, larvae in all stages of growth ; 

 and on the portion first laid dry, some pupae. The dates here given refer 

 to the appearance and development of the insect on one particular bog 

 only 5 the dates vary according to circumstances on other bogs. 



White hellebore had been used by Dr. Brakeley in previous seasons 

 with good success, and as soon as the larvae became dangerous he 

 turned his attention to them. On the part not flowed larvae were abun- 

 dant in May, and they were given a dose of hellebore ; to ascertain 

 what effect it had I covered a space of about three square feet, and this 

 was thereafter not dosed. 



The hellebore was applied in the form of powder, with a bellows con- 



