86 THE CANADIAN ENTOMOLOGIST 



NOTES ON THE LIFE-HISTORY AND EARLY STAGES OF BRACHYS 

 OVATUS WEB., AND BRACHYS AEROSUS MELSH. 



BY HARRY B. WEISS AND ALAN S. NICOLAY, NEW BRUNSWICK, N.J. 



Packard in his "Forest Insects" records B. aerosus as occurring on oak early 

 in summer in Maine and late in May near Providence, R.I., and states that 

 Gillette (Canad. Ent. July, 1887) reared it from larvae in poplar leaves, the mines 

 being finished in October and the beetles appearing early the following May. 

 Concerning B. ovatiis, this species is recorded by Packard as follows "on laurel 

 oak; imago issues latter part of April and early May (Riley's unpublished notes)." 

 Gillette also reports rearing the beetle from a larva mining a leaf of either red 

 or black oak. Felt (N. Y. State Mus. Mem. 8; 2, p. 512-3) states that B. 

 aerosus was taken while feeding on elm during the latter half of May, and that 

 B. ovatiis was common on scrub oak the latter part of May and June. Blatchley 

 in his 'iJColeoptera of Indiana" records aerosus as throughout the state, frequent. 

 May 16-June 18, occurring on oak, hickory, elm and ovatiis also as throughout 

 the state and frequent, May 16-July 13, on oak in the leaves of which the larvae 

 dwell. According to Smith (Rept. N. J. State Mus. 1909) aerosus is found 

 throughout New Jersey, not rare, on oak, May, June and ovatus is common 

 throughout the state, June to August on oak. Burke (U. S. Dept. Agric. Bull. 

 No. 437, 1917) summarizes the distribution, common habits and host trees of 

 the genus Brachys as follows: — "Eastern and Central States, leaf miner in 

 leaves: Popiiliis ?, alder (Alnus), Fagus ?, chestnut (Castanea), oak {Quercus), 

 Ulmus ?, and Acer}'' 



In New Jersey, we have found the distribution of both species to be as 

 reported by Smith, and have observed the adults feeding on foliage as follows: 

 B. ovatus on elm {Ulmus americana), sugar maple (Acer saccharum), white oak 

 {Quercus a/6a), chestnut oak {Q. prinus), pin oak {Q. palustris), chestnut {Castanea 

 dentata), scrub oak {Q. ilicifolia), black oak {Q. velutina), post oak (Q. minor), 

 beech (Fagus ferruginea), and hickory (Hicoria glabra) with the various species 

 of oaks as preferred food plants; B. aerosus feeding on beech (F. ferruginea), 

 linden (Tilia americana), witch hazel (Hamamelis virginiana), elm (Ulmus 

 americana), chestnut (C. dentata), sugar maple (A. saccharum), red maple 

 (A. rubrum),and various species of oaks with the oaks as preferred food plants, 

 although quite a few adults were taken while feeding on red maple and beech. 



The feeding of both species is quite characteristic. The beetles feed on the 

 upper leaf surfaces usually near the edges consuming the tissue between the 

 larger veins and working, as a rule, along a large vein. This habit results in 

 feeding areas which are bounded on one or more sides by straight edges or lines 

 giving the injury a sort of ragged geometrical appearance. After much feeding 

 has been done at one spot, the small amount of remaining uninjured tissue 

 weathers away in the course of time, resulting in irregular holes. 



The mines of both species are somewhat irregular and blotch-like and may 

 be found on any part of a leaf, the majority, however, occurring near the edge. 

 As a rule each mine contains only one larva, and is found on a leaf which is 

 comparatively uninjured by adult feeding. Aerosus mines take up only a small 

 portion of a leaf, while an ovatus larva will frequently mine one-half or more of a 

 medium-sized leaf. The mines of both species are visible on both leaf surfaces, 

 more so on the upper where they appear as brown dead spots or areas. Some 



April, 1919 



