108 



PSYCHE. 



[July 1S91. 



TWO NEW LEPIDOPTEROUS BORERS. 



BY OTTO LUGGER, ST. ANTHONY PARK, MINN. 



To the long list of Injurious borers 

 infesting cultivated and wild plants two 

 new species must be added which, in 

 Minnesota, are of especial interest, as 

 they cause great damage to some of our 

 trees, and even threaten to destroy them 

 entirely in some regions. 



All visitors to the Twin Cities admire 

 our groves of oaks, chiefly composed of 

 peculiarly branched and gnarled burr- 

 oaks, and dark and straight red-oaks. 

 The former, though badly infested by 

 numerous species of insects, seems to be 

 proof against any lasting injury by them. 

 The tree is in fact so well protected with a 

 corky bark, even found upon the young- 

 est twigs, that both insects and intense 

 cold seem to be powerless. This is 

 quite different, however, with our red- 

 oak, a tree of much quicker growth and 

 but slightly protected by thin and glossy 

 dark bark, at least when still young and 

 not wrinkled by old age. Nature seems 

 to have endowed the former, like a good 

 mother, with a warm and enduring coat 

 against insects and the inclemencies of 

 winter, and to have treated the red- 

 oak like the step-mother so much fabled 

 about. The red-oak seems to have a 

 very great attraction for all kinds of 

 boring insects, but notwithstanding its 

 wonderful power to repair injuries and 

 to heal wounds made upon its bark and 

 wood — a power not shared by the burr- 

 oak — the tree is a doomed one, provid- 



ing no steps are taken to protect it as 

 well as it deserves. But all advice to 

 protect any of our native trees is usually 

 received with a smile that is more or 

 less unpleasant to the true lover of nature, 

 as it contains the elements of contempt, 

 ridicule and derision for the adviser. 



Among the worst borers of the red- 

 oak are several lepidopterous larvae, but 

 chiefly those of Prionoxystus querci- 

 perda (Fitch), P. robiniae (Peck) and 

 Trochilium lugger i. The first (pi. 3, 

 figs. 1 and 2) , as well as the second spec- 

 ies, are insects described long ago ; the 

 latter, and the most injurious one in this 

 regior, has been described by H. Ed- 

 wards, our authority in this family of 

 insects. Below is his description, illus- 

 trated by pi. 3, fig. 3. 



Trochilium luggeriw. sp. Upper side of head 

 black, orbits of eyes bright lemon yellow. 

 Face black. Palpi black at the base, otherwise 

 lemon yellow. Thorax with the disk black, 

 with short erect downy hairs. Collar, patagia, 

 spot at the base of the wings, and a broad 

 streak at base of thorax conspicuously lemon- 

 yellow. Antennae chestnut brown above, dull 

 orange beneath. Tibiae orange, tarsi some- 

 what of a darker shade. Abdomen black, 

 anal tuft pale orange, with bright yellow 

 band at the posterior edge of all segments, 

 those of the posterior segments much 

 widened. Forewings thinly clothed with 

 scales the costa narrowly dull orange as is also 

 the oblique rather indistinct discal mark at the 

 end of the cell. The space from vein 2 to 

 vein 5 clear of scales behind the cell. Hind 



