The chironomid season starts from ice off in the spring and continues through to freeze over in the fall in the Kamloops area lakes. These gorgeous little creatures are a primary food source for trout and are available for feed in both the larvae (bloodworm) and pupae (chironomid) stages of its life cycle.
The explosive rainbow trout found in these productive lakes tend to key in on two main characteristics when feeding on chironomids during the open water season… the first category is related to size and the second relates to color. This article will discuss chironomid size.
Experience and observation suggests that chironomid size matters depending on the season. When the water is at its coldest (in the spring and fall) the chironomid patterns to use are quite small, usually in the #14 to #22 range, short to 4XL in length. As the water warms, larger chironomids and bloodworms start to appear ( note: chironomid patterns smaller than size #18 are difficult to tie, cast and fish).
The major chironomid hatches in the Kamloops area lakes occur from mid-may and last until mid-June and usually the average size of the insect balloons to size #12 but may vary to as large as #10. Smaller sizes of #14 to #16 are also common.
By mid-June the water has warmed significantly, spurning on other insect hatches that the trout key in on. Damsel, dragon, caddis and mayfly nymphs are abundant and the trout key in on the flavor of the day and chironomids, although available, seem to take a back seat on the trout menu.
July and August tend to be very warm in the Kamloops area which brings the temperature of the local lakes to 18C-20C (64F-69F). This is when the famous “bomber” hatches prevail, producing both larvae and pupa up to 3cm in length. Using #8 4XL patterns is not unusual and when the trout are feeding, these bombers also produce some of the biggest trout of the year.
Naturally, water temperature decreases as fall weather sets in and with that, you can expect to see the average chironomid size decrease. Late season chironomid sizes are smaller,much like early spring, with size #14 to #22 prevailing.
Keep this rule of thumb in mind when trying to match the hatch with chironomids during the open water fishing season in the Kamloops area lakes.