How to Place and Read Sticky Monitors in a Kitchen

Why this matters

A sticky monitor that is not numbered, dated and counted is a glue board, not a monitor. The difference shows up on the third visit, when the customer says "they're still here" and the tech has no way to say where, how many, or whether it is better or worse than a month ago. Counted monitors turn a kitchen into a map: they show which corner is producing, they show the treatment working or not, and they catch the hot zone moving before the customer does. This card owns placing and reading them. What count justifies what action on a commercial account is a separate question. See related: IPM Action Thresholds for an Account.

What a monitor can and cannot tell you

A monitor catches what walks across it. That makes it a relative measure: it compares this position to that one, and this visit to the last, at the same positions. It is not a population count. Twelve cockroaches on a board does not mean twelve in the kitchen, and zero on a board in the middle of an open floor means nothing at all, because German cockroaches travel edges, not open floor.

Three things a monitor tells you that an inspection alone does not:

• Direction of change, if positions stay fixed between visits.
• Life stage. Small nymphs on a board mean harborage within a short distance, because young nymphs do not travel far. Adults alone can be wanderers.
• Activity at night in places you cannot inspect during the day, such as under the range.

Two things it will mislead you on: a board that has gone dusty or wet stops catching and reads as success, and a board moved six inches between visits is a new data point, not a continuation.

The map

The diagram is the kitchen from the worked example: counters along the north wall with range, sink and dishwasher; refrigerator on the east wall; pantry in the southwest corner; back door in the south wall.

 KITCHEN PLAN                                N
 +------------------------------------------+
 | M1  [ RANGE ]  [ SINK ]  [ DW ]       M2 |
 |     M3 under   M4 in                     |
 |     range,     sink base,          [REF] |
 |     back wall  back corner          M5   |
 |                                     side |
 +----+                                     |
 |PANT| M6 pantry floor, corner             |
 |RY  |                                     |
 +----+-------------[ BACK DOOR ]-----------+
                     M7 inside, hinge side

M1 and M2 sit on the floor at each end of the counter run where the toe kick meets the side wall. M3 is slid under the range against the back wall. M4 is inside the sink base at the back corner. M5 is on the floor between the refrigerator side and the wall. M6 is in the pantry floor corner. M7 is inside the back door at the hinge side.

Setting them

1. Number and date every board before it goes down. Write the position number and the date on the board itself, in marker, and the same on the account's monitor map. A board with no date cannot tell you whether 6 catches is a week or two months.

2. Place against an edge, opening along the line of travel. Flush to the wall or cabinet edge, with the open side facing along the wall, not out into the room. A cockroach running the junction of floor and wall walks into a board laid along it; one set a hand's width out gets walked around.

3. Put boards where the inspection found activity, plus one or two control positions. Hot positions from the flashlight inspection (see related: How to Run a Flashlight Inspection for Cockroaches) get boards so you can watch them fall. A couple of positions away from known activity (here M1 and M6) tell you whether the infestation is spreading.

4. Do not move appliances to place them. Slide M3 under the range with a reacher or a strip of stiff card. Pulling a gas range out strains the flexible connector, and a connector disturbed by you is your problem; if a range has to come out, the customer or the shop's procedure for gas appliances decides that, not the monitor. Refrigerators are heavy and tip; slide the board in at the side.

5. Record counts by number at every visit, before you touch anything. Count adults and nymphs separately. Note egg cases if present. Read before you bait or treat, because the board is evidence of the period just ended.

6. Replace on condition and on schedule. A board is replaced when it is dusty, wet, greasy, or more than about half covered, and in any case at a fixed number of visits your shop sets (every visit on a heavy account, every second visit on a light one is a common start). The new board goes in the same spot with the same number and a new date.

Positions that lie

Some spots produce counts that mean something other than what they appear to mean. Set boards there knowingly or not at all.

• On the floor of a leaking sink base. A board on a damp floor stops catching within days and reads as success. Set M4 on the dry side panel joint, or fix the leak first and write the leak up.
• Right beside a bait placement. Foragers converging on fresh bait load the board for reasons unrelated to harborage. Keep boards a short distance off the bait spots, at the same offset every visit.
• At an exterior door. M7 catches what walks in from outside. American, smoky brown and other peridomestic species turning up there are not part of the German cockroach count, and they mean a door sweep or threshold problem rather than a kitchen infestation. Log them by species on a separate line; for ID see 'Cockroach Species Identification - Beyond German'.
• Under a toaster or beside the stove top. Crumbs and grease cover the glue and the board fails early, and heat near a burner can soften it.

Worked example: three visits on one kitchen

The kitchen in the diagram is a residential account on a German cockroach program run per 'German Cockroach IPM'. The first visit placed seven boards and gel bait (placement technique in 'How to Place Gel Bait in a Kitchen'). Each later visit is about two weeks after the one before. Counts are adults plus nymphs per board for the period since the last read.

 MONITOR LOG, ACCT 2217 KITCHEN
 pos  location            V2    V3    V4
 M1   NW floor, range end   0     0     0
 M2   NE floor, DW end      1     0     0
 M3   under range           6     4     2
 M4   sink base corner     14     9     3
 M5   fridge side           3     5     7
 M6   pantry corner         0     0     0
 M7   back door hinge       0     1     0
      TOTAL                24    19    12
 replaced: V3 all (dust); V4 M4, M5

Visit 2. Total 24, with M4 alone at 14, more than half the total, mostly small nymphs. The sink base is the harborage, which matches the inspection. M3 at 6 says the range is the second hot spot. M1 and M6 at zero say it has not reached the far ends of the room. Action: more bait at the sink base positions.

Visit 3. Total 19, down 5 from 24. M4 fell from 14 to 9 and M3 from 6 to 4, the treatment is reaching the sink and range. But M5 rose from 3 to 5. Two catches is small, and one visit is not a trend, so you note it and inspect behind the refrigerator grille without changing anything else. All seven boards replaced because a renovation next door left them dusty, each with the same number and a fresh date.

Visit 4. Total 12, down 7 from 19. M4 is down to 3 and M3 to 2. M5 rose again, from 5 to 7, and is now the highest board in the kitchen. The total has fallen at every visit, 24 then 19 then 12, and a tech reading only the total would call it nearly won. Read by position, the population has been knocked down at the sink and the range, and a second center has established at the refrigerator. The nymphs on M5 confirm harborage close by. Action: pull the refrigerator grille, inspect the motor compartment and the back of the unit, and add bait there.

What the log let you say to the customer: "The sink cabinet was the main nest and it's down by about four fifths, 14 to 3. There's a second spot behind the fridge, and that's where I'm working today."

Reading the trend

Compare positions to themselves, not to each other's raw numbers. A board under a warm range will always catch more than one by the back door at the same population. What matters is each board's direction.

Look for the board moving against the total. That is the hot zone shifting. It is the single most useful thing a monitor log shows, and it only shows if counts are kept by position.

Weigh stage, not just count. A rise made of adults can be wanderers pushed out of a treated area. A rise made of small nymphs means a new harborage nearby.

Give it two reads before calling it. One visit's change of two or three catches is noise. The same direction on two consecutive reads at the same position is a trend.

A zero needs a working board. Before you write zero, check the board is clean and sticky. A dusty board that reads zero is a missing reading, and it should be logged as missing.

What changes the method

Commercial kitchens need more boards, under equipment and at dock doors, and usually a count threshold the account has agreed to. The count becomes part of the service record an auditor reads, so the numbering has to match a posted map. See related: The Commercial Pest Sighting Log.

Other pests. Stored-product moths and flies need different monitors (pheromone traps, light traps) and different placement. This method is for crawling insects on floors and in cabinets.

A customer who throws boards away. Explain what they are for, put them where they will not be kicked, and note on the record when a position went missing; a gap is better than a fabricated number.

The finish test

The account carries a monitor map with every position numbered and described, and a log with a count by position, by stage where possible, for every visit, with replacements noted. Another tech arriving cold can find every board, read it, add a column and say which position is the hot zone.

References

• See related: German Cockroach IPM
• See related: IPM Action Thresholds for an Account
• See related: How to Run a Flashlight Inspection for Cockroaches
• See related: How to Place Gel Bait in a Kitchen
• See related: The Commercial Pest Sighting Log