236 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



Paris green injures tlie tree more tlian the London purple. Three-fourths of a pound 

 of Paris green to a barrel (thirtv-six or forty gallons) of water, with three quarts of 

 flour or three-quarters of an ounce of Paris green to a bucket of water, may be regarded 

 as a poison mixture of medium or average strength for treating elms affected by these 

 beetles. 



When many trees are to be sprayed a cart or wagon may be used to haul the poison 

 in a large barrel provided with a stirrer, force pump, skid, etc. The force pump was 

 described and figured in the annual report of the entomologist for 1882. It is double- 

 acting and very powerful, giving strong pressure to disperse the liquid far and finely, 

 and about a pailful of poisoned water was sprayed upon each tree. When only two 

 or three were to be treated an aquapult or other bucket pump was used to force the 

 poison from a bucket carried by baud. Connected with either pump is a long flexible 

 pipe, with its distal part stiff, and serving as a long handle whereby to hold its 

 terminal nozzle beneath the branches or very high up at a comfortable distance from 

 the person managing it. To the hose is attached a bamboo pole, the partitions of 

 which may be burned out with a hot iron rod. With this ap})aratus a tree can be 

 quickly sprayed, and a large grove or row of trees along a street treated in a short 

 time. It is equally adapted for forestry use in general, and for orchards, when the 

 trees are not in frnit. 



The egg. — In each group (Fig. 81 e, magnified), and so firmly fastened to the leaf that 

 they can only be detached with great care without breaking the thin and brittle 

 shell. The number of eggs in each group varies from four or five to twenty or more. 

 Very rarely only three eggs are seen in one group, but we never found less than that 

 number. The egg itself is oblong oval, obtusely, but not abruptly, pointed at tip, of 

 straw yellow color, its surface being opaque and beautifully and evenly reticulated, 

 each mesh forming a regular hexagon, as shown, highly magnified, in Fig. 81 /. The 

 form of the eggs is not quite constant, some of them, especially those in the middle 

 of a large group, being much narrower than others. The duration of the egg state is 

 about one week. 



Larva. — The general shape of the larva is very elougate, almost cylindrical, and 

 distinctly tapering posteriorly in the early stages, but less convex and of nearly equal 

 width when mature. The general color of the young larva is yellowish-black, with 

 the black markings comparatively larger and more conspicuous, and with the hairs 

 arising from these markings much longer and stiffer than in the full-grown larva. 

 With each consecutive molt the yellow color becomes more marked, the black mark- 

 ings of less extent and of less intense color, and the hairs much shorter, sparser, and 

 lighter in color. A nearly full-grown larva is represented in Fig. 80 g, and in this the 

 yellow color occupies a wide dorsal stripe and a lateral stripe each side. The head 

 (excepting the mouth-parts and anterior margin of the front), the legs (excepting a 

 ring around the trochanters), and the posterior portion of the anal segment are always 

 black. The first thoracic segment has two large black spots on the disk, of varying 

 extent, and often confluent. The following segments (excepting the anal segment) 

 are dorsally divided by a shallow tran verse impression into two halves, and the black 

 markings on these halves are arranged as follows : two transverse dorsal markings, 

 usually confluent, as shown in our figure ; two round and sublateral spots ; the tips of 

 the lateral tubercles are also black. The abdominal joints of the ventral surface have 

 each a transverse medial mark, and two round sublateral spots of black color. Stig- 

 mata visible as small umbilicate spots between outer sublateral series of dorsal mark- 

 ings and lateral tubercles. The yellow parts of the upper side are opaque, but those 

 of the under side shining. The black markings are polished, piliferous, and raised 

 above the remaining portions of the body. 



Pupa. — Of brighter color than the larva, oval in shape, and strongly convex dor- 

 sally. It is sparsely covered with moderately long but very conspicuous black bris- 

 tles, iri'egularly arranged on head and thorax, but in a transverse row on each fol- 

 lowing segment. The pupa state lasts from about six to ten days. 



