THE PRACTICAL ENTOMOLOGIST. 



Many motlis lay their eggs in patches, in places 

 easy of access, and in this case it costs us little trou- 

 ble to destroy our enemies before they have done us 

 any injury. I shall mention here the gipsy-moth 

 (.Bombjj.c dhjxir), which lays its eggs in large cir- 

 cular or oval spots on the bark of trees, or hedges, 

 and covers them with a yellow wool. If we destroy 

 these eggs, one heap of which often contains 300, 

 in autumn or spring our fruit-trees will be secured 

 from one of their most dangerous enemies.* 



" It is equally easy to destroy in the egg the yel- 

 low-tail moth (Bomhyx chri/sorrJioea), which is no 

 less injurious to our orchards. This moth lays its 

 eggs on the leaves of the fruit trees in a long nar- 

 row heap, and covers them with gold-colored hair, 

 which makes them very conspicuous. Pulling off 

 and destroying these leaves secures the garden from 

 another dangerous enemy. 



"The satin-moth (Bonibi/x salicis), which not 

 only attacks willows, but poplars, which it prefers, 

 and strips our avenues almost every year, is very 

 difficult to be extirpated in the larva state, as it 

 spreads singly all over the tree. But when we know 

 that the female in the month of July has laid her 

 eggs like mother-of-pearl spots, chiefly on the bark 

 of the poplar, a few ordinary laborers with their 

 knives might loosen these eggs from the bark and 

 destroy them. 



" No effectual means can be taken against other 

 insects except in their larva or pupa states, because 

 they deposit their eggs singly, or in concealed places, 

 or because it is difficult to distinguish them from 

 the objects on which they are placed. 



" It is impossible to destroy the dreaded proces- 

 sionary caterpillar {Bomhyx procrssionra) in the 

 moth state, because it flies in the night. It is 

 almost as difficult to destroy its eggs, from their 

 similarity in color to the oak bark, which prevents 

 their being observed, and also from their being dis- 

 tributed all over the branches in small longish 

 patches. The caterpillars, however, are gregarious; 

 they sit in the day time on the stem or large branches, 

 so that hundreds can be destroyed at a blow, by 

 means of a wisp of straw, or a bundle of old rags. 

 In the pupa state they are also easily destroyed, as 

 they are usually found by hundreds in a nest, and 

 hang like brown excrescences all over the trunk. 



" The most essential and necessary means to be 

 opposed to the serious injuries caused by insects, 

 consists in the universal dissemination of the know- 

 ledge of the natural history of hurtful insects among 



*A most satisfactory proof of the superior advantages 

 arising from hand labor in the destruction of insects, has 

 recently been given by M. V. Audouin. who was charged 

 by a commission of the Academic des Sciences to investi- 

 gate the habits of a small moth, whose larva is found to 

 be exceedingly injurious in vineyards in France. During 

 the month of August, women and children were employed 

 during four days in collecting the patches of eggs upon 

 the leaves, during which period 186,900 patches were col- 

 lected, which was equal to the destruction of 11,214,000 

 eggs. In twelve days from twenty to thirty workers de- 

 stroyed 40,182,000 eggs, which would have been hatched 

 in the course of twelve or fifteen days. The number of 

 perfect insects destroyed in a previous experiment by an 

 expensive process was only 30,000. — See Loudon's Gar- 

 deners' Mag. for November, 1S37. 



farmers, gardeners, foresters, and particulnrly among 

 those who are in any way connected with agricul- 

 ture. This knowledge should be spread as well by 

 verbal expositions in public institutions as by books 

 easy of comprehension." 



The Joint-Worm. 



BY BENJ. D. WALSH, M. A. 



Since my observations on the Joint-worm were 

 printed in the second number of the Practical 

 Entomologist, specimens of the same Insect that 

 came under the notice of the Canada Farnur, have 

 been obligingly forwarded to me by Mr. Eiddell, of 

 Cobourg, C. W.; and it is nothing whatever but the 

 common Hessian Fly (^Cecidomyia destructor, Say) 

 in its "flaxseed" state. Hence, for any future in- 

 vestigation of this important subject, I must depend 

 solely upon specimens sent me from other rjuarters. 

 The two insects are readily distinguishable b}' the 

 following criterion : — The Hessian Fly larva lies in 

 the space between the straw and the .shank of the 

 leaf that enwraps the straw above each knot. The 

 Joint-worm lies inside the straw itself, in a hard and 

 more or less woody swelling just above the knot, or 

 sometimes in the knot itself, or in the swollen and 

 distorted shank of the leaf. Very frequently the 

 Hessian Fly is imbedded in a deep cavity formed 

 on the outside of the straw ; but a little attention 

 will soon show that this cavity does not penetrate 

 the skin of the straw, any more than a bruise in an 

 apple penetrates the skin of the apple. 



Dr. Fitch devotes twenty-one pages of his recently 

 published Reports (6fh — dfh M Y. Rep. pp. 14-1 — 

 165) to this subject, without throwing much new 

 light upon it, and seems to have changed his views 

 somewhat, even during the printing of those twenty- 

 one pages. On page 152 he says, " I must confess 

 that now, when I come to cast over all the evidence 

 which we have in relation to this subject, I feel less 

 confident than I have been for a few years past, that 

 this Eurytoma [i. e. Chalets fly] is the real parent 

 of the Joint-worm." But only twelve pages after- 

 wards he adds — " I ought not to dismiss the subject 

 without remarking, that I do not in the least doubt, 

 that they [i. e. the Chalcis flies] are the real cause 

 of the disease which we see in the grain." (p. 164.) 



That Dr. Fitch, like the rest of us, is not infalli- 

 ble, is shown by the fact, that he throughout mis- 

 takes the well-known V-shaped or Y-shaped " breast* 

 bone" of the larvae of the Gall-gnata, (or as he rather 

 incorrectly calls them Gall-flies,') for a pair of jaws ! ! 

 (See p. 150, &c.) Whereas his so-called "jaws" 

 are not located on the head, but on the segment im- 

 mediately behind the head; and further than that, 

 the two prongs of the V or Y are perfectly immove- 



